AMS AS3668 Data Sheet

Data Sheet
AS3 6 6 8
4 C h a n n el B r e a t hl i ght Cont r oller
1 General Description
2 Key Features
The AS3668 is a 4-channel LED driver designed to produce lighting
effects for portable devices. A highly efficient charge pump enables
LED driving over full Li-Ion battery voltage range. The device is
equipped with an internal program memory, which allows control of
LED patterns even without processor control. This helps the whole
system to save power and extend for example battery life time in
every mobile application. The AS3668 maintains excellent efficiency
over a wide operating range by automatically selecting the best
charge pump gain based on the LED forward voltage requirements
and the device input voltage.
High efficiency capacitive 60mA charge pump with 1:1 and 1:2
Furthermore the chip supports an automatic power-save mode which
gets active when LED outputs are not active. The special powersave mode has a extremely low current consumption below 10μA
(typ.).the AS3668 has an I2C-compatible control interface which
supports two slave address without having a dedicated address
selection pin. For fancy lighting effects synchronized with an audio
signal the device supports special digital filter modes in order to
make music literally visible on the 4 independent configurable
current sources.
Integrated “easy to use” pattern generator for breathlight LED
The AS3668 is available in a very tiny 12-pin WL-CSP
(1.255x1.680mm) 0.4mm pitch package.
mode
Automatic mode switching for charge pump
Automatic Pattern Mode without digital control
Highly accurate 4 Channel High Side 25.5mA current sources
Audio Controlled Lighting with internal digital filters
Charge Pump with soft start and overcurrent/short circuit pro-
tection
function with logarithmic 12bit dimming
Small application circuit
Minimum number of external components
Available in 12-pin WL-CSP (1.255x1.680mm) with 0.4mm pitch
3 Applications
The product is perfect for Mobilephones, MP3 Player, Portable
Navigation Devices, Digital Cameras, USB Dongles/Modems, Game
Controllers and can be used for fun and indicator lights, backlighting
and as programmable current sources.
Figure 1. AS3668 Block Diagram
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AS3668
Data Sheet - A p p l i c a t i o n s
Contents
1
2
3
4
General Description .................................................................................................................................................................. 1
Key Features ............................................................................................................................................................................ 1
Applications .............................................................................................................................................................................. 1
Pin Assignments ....................................................................................................................................................................... 4
4.1 Pin Description
.....................................................................................................................................................................................5
5 Absolute Maximum Ratings ...................................................................................................................................................... 6
6 Electrical Characteristics .......................................................................................................................................................... 7
6.1 Timing Characteristics
..........................................................................................................................................................................9
6.2 Timing Diagrams ..................................................................................................................................................................................10
7 Typical Operating Characteristics ................................................................................................................................................11
8 Detailed Description ............................................................................................................................................................... 14
8.1 Charge Pump
8.1.1
8.1.2
8.1.3
8.1.4
8.2
.....................................................................................................................................................................................14
Charge Pump Mode Switching ..................................................................................................................................................15
Soft Start ....................................................................................................................................................................................15
Unused Charge Pump ...............................................................................................................................................................15
Charge Pump Control Register ..................................................................................................................................................16
Current Sources
.............................................................................................................................................................................16
8.2.1 Unused Current Sources ...........................................................................................................................................................17
8.2.2 Current Source Registers ...........................................................................................................................................................18
8.3 Power - On Reset
8.4 VBAT Monitor
...............................................................................................................................................................................19
.....................................................................................................................................................................................20
8.4.1 VBAT Monitor Registers . ..........................................................................................................................................................21
8.5 Temperature Supervision
8.6 I²C Serial Interface Bus
...................................................................................................................................................................21
......................................................................................................................................................................22
8.6.1 I²C Device Address Byte ............................................................................................................................................................24
8.6.2 Command Byte ..........................................................................................................................................................................24
8.6.3 I²C Device Address Selection ....................................................................................................................................................25
8.7 Operating Modes
................................................................................................................................................................................25
8.7.1 GPIO/AUDIO_IN Automatic Pattern Start-up Mode ..................................................................................................................27
8.8 General Purpose Input / Output
.........................................................................................................................................................29
8.8.1 Unused General Purpose Input / Output ...................................................................................................................................30
8.8.2 GPIO Control Register. ..............................................................................................................................................................30
8.9 Audio Input
.........................................................................................................................................................................................30
8.9.1 Audio Control Register .............................................................................................................................................................32
8.10 LED Pattern Configuration
8.10.1
8.10.2
8.10.3
8.10.4
8.10.5
8.10.6
...............................................................................................................................................................34
Single Pulse Mode ...................................................................................................................................................................34
Multiple Pulse Mode ................................................................................................................................................................ 35
Frame Mask Mode ...................................................................................................................................................................36
Frame Start Delay Mode ..........................................................................................................................................................37
GPIO Toggle Mode ..................................................................................................................................................................37
LED Pattern Control Registers ...............................................................................................................................................38
9 Register Map
........................................................................................................................................................................ 45
10 Application Information ........................................................................................................................................................ 48
10.1 LED Software Implementation Examples
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.........................................................................................................................................48
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Data Sheet - A p p l i c a t i o n s
10.1.1
10.1.2
10.1.3
10.1.4
10.1.5
Simple Breathlight Pattern with one LED .................................................................................................................................48
Dual Pulse Pattern with one LED ............................................................................................................................................48
RGB LED Pattern ....................................................................................................................................................................49
Parallel Up - Dimming ..............................................................................................................................................................50
Parallel Down- Dimming ..........................................................................................................................................................50
10.2 Hardware Examples
.........................................................................................................................................................................52
11 Package Drawings and Markings ......................................................................................................................................... 57
12 Ordering Information ............................................................................................................................................................. 60
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AS3668
Data Sheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Assignments 12-pin WL-CSP (1.255x1.680mm)(Top View)
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AS3668
Data Sheet - P i n A s s i g n m e n t s
4.1 Pin Description
Table 1. Pin Descriptions
Pin Name
Pin Number
Description
VBAT
C2
Positive Power Supply Input for AS3668.
GND
D2
Signal and Power Ground. Provide a short, direct PCB path between this pin and the negative side of the output capacitor of the charge pump capacitor CVCPOUT.
SCL
B3
Serial Clock Input for the two wire I2C interface.
SDA
C3
Serial-Data I/O for I2C interface. This pin is a open drain digital I/O which requires a pull up
resistor for data transfer.
General Purpose Input/Output or Audio Input. Depending on AS3668 configuration this
pin provided three different features. It can either be configured as general purpose input/
1
output or as analogue audio input for music playback synchronization of AS3668 with an
audio source. Furthermore it is possible to use it as power up pin starting up with a default
PWM pattern sequence for LED1. If the pin is not used it is mandatory to connect it to
ground.
GPIO/AUDIO_IN
D3
CURR1
B2
CURR1 Output. This pin is a current source output which can be used to operate a LED. The
current source is internally connected to VCP. If the AS3668 is powered up with GPIO/
AUDIO_IN pin this current source is active with a default PWM pattern.
CURR2
C1
CURR2 Output. This pin is a current source output which can be used to operate a LED. The
current source is internally connected to VCP.
CURR3
A1
CURR3 Output. This pin is a current source output which can be used to operate a LED. The
current source is internally connected to VCP.
CURR4
D1
CURR4 Output. This pin is a current source output which can be used to operate a LED. The
current source is internally connected to VCP.
VCP
B1
Charge Pump Output. This pin requires an external blocking capacitor. The capacitor must
be placed as close as possible to VCP terminal.
A2
Charge Pump Flying Capacitor. This is the positive terminal for the charge pump flying
capacitor. The capacitor should be placed as close as possible to AS3668. In addition it is
mandatory to keep the signal trace between the capacitor and CP terminal as short as
possible.
A3
Charge Pump Flying Capacitor. This is the negative terminal for the charge pump flying
capacitor. The capacitor should be placed as close as possible to AS3668. In addition it is
mandatory to keep the signal trace between the capacitor and CN terminal as short as
possible.
CP
CN
1. The output is an open-drain output only. Therefore an external Pull-Up resistors is required for output operation.
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AS3668
Data Sheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of
the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 7 is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Table 2. Absolute Maximum Ratings
Parameter
Min
Max
Units
VBAT, VCP, CN, CP to GND
-0.3
7
V
VCP to GND
-0.3
7
V
LED1, LED2, CURR3, CURR4 to GND
-0.3
7
V
SCL, SDA, GPIO/AUDIO_IN to GND
-0.3
7
V
Input Pin Current without causing
latch up
-100
+100
mA
Comments
Protection diode between VCP and GND
At 25ºC, Norm: EIA/JESD78
Electrostatic Discharge
ESD HBM (CURR1 to CURR4)
2
kV
ESD HBM (all other pins)
2
kV
ESD MM
100
V
JEDEC JESD22-A115
ESD CDM
500
V
JEDEC JESD22-C101
Storage Temperature Range
-55
+125
ºC
0.83
W
+125
ºC
60
°C/W
85
%
JEDEC JESD22-A114
Temperature Ranges and Storage Conditions
Continuous Power Dissipation
Storage Temperature Range
Junction to Ambient Thermal Resistance (JA)
Humidity non-condensing
Moisture Sensitive Level
Package Body Temperature
-55
2
5
1
Internally limited (over temperature protection)
1
Represents a max. floor life time of unlimited.
+260
ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State Surface
Mount Devices”.
1. Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ = 140°C (typ.) and
disengages at TJ = 135°C (typ.).
2. Junction to ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power
dissipation exists, special care must be paid to thermal dissipation issues in board design.
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AS3668
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
VBAT = 3.6V, CBAT = CVCPOUT = 1μF, CFLY = 470nF, TAMB = -30ºC to +85ºC, typical values @ TAMB = +25ºC (unless
otherwise specified) .
Table 3. Electrical Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Unit
5.5
V
3
μA
General Operating Conditions
Supply Voltage
VBAT
2.7
Standby supply current
IVBAT
Normal Mode supply
current
fOSC
Internal Oscillator
Frequency Accuracy
TAMB
Operating Temperature
SCL = 0V and GPIO = 0V
0.2
SCL = VBAT and SDA = VBAT, no I2C communication
and no internal block enabled
10
μA
Charge pump in 1x mode, no load, current source outputs
disabled
70
μA
Charge pump in 2x mode, no load, current source outputs
disabled
2.5
mA
-10
1
-30
25
+10
%
85
°C
Charge Pump
ROUT
Charge Pump Output
Resistance
fSW
Switching Frequency
tON
VCP Turn-On Time
2
Operating Mode 1:1
2
Operating Mode 1:2; VBAT = 3.0V
20

1
MHz
no load, current sources CURR1 - CURR4 deactivated
30
μs
IOUT = 50mA, current sources CURR1 - CURR4
deactivated
40
μs
PWM = 0%
0.1
Current Sources
ILEAK
Leakage Current
(LED1 to CURR4)
IMAX
Maximum Source Current
Outputs CURR1 to CURR4
IOUT
Output Current Accuracy
Output Current set to 25.5 mA
-15
+15
%
IMATCH
Matching Accuracy
Output Current set to 25.5 mA
-10
+10
%
fLED
Switching Frequency
PWM mode with internal oscillator
1
25.5
μA
mA
122
Hz
Logic Interface
Logic Input SCL, SDA and GPIO/AUDIO_IN
VIL
Input Low Level
VIH
Input High Level
IIN
Input Current
VOLGPIO
Low Level Output voltage
VHYS
Hysteresis
fEXT
External PWM input
Pin GPIO/AUDIO_IN at 4mA
0.52
V
1.38
VBAT
V
-1.0
1.0
μA
0.2
V
0.1
V
Only possible with GPIO/AUDIO_IN
1
MHz
2.5
VPEAK
Analogue Input
Analogue Audio Input GPI/AUDIO_IN
VAUDIO
Input Signal Level
RAUDIO_IN
Audio Input Resistance
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Audio Preamplifier Gain = -6dB
400
kΩ
Audio Preamplifier Gain = +20dB
60
kΩ
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AS3668
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 3. Electrical Characteristics (Continued)
Symbol
Parameter
CAUDIO_IN
Input Capacitance
AAudio
Programmable Amplifier
Gain
Condition
Min
Typ
Max
10
-6
Unit
pF
25
dB
1. Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ = 140°C (typ.) and
disengages at TJ = 135°C (typ.).
2. Turn-on time is measured from the moment the charge pump is activated until the VCP crosses 90% of its target value
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AS3668
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6.1 Timing Characteristics
VBAT = 3.6V, CBAT = CVCPOUT = 1μF, CFLY = 470nF, TAMB = -30ºC to +85ºC, typical values @ TAMB = +25ºC (unless
otherwise specified) .
2 1
Table 4. Electrical Characteristics I C
Symbol
Parameter
Condition
Min
Typ
Max
Unit
400
kHz
I2C mode timings - see
fSCLK
SCL Clock Frequency
1/35ms
tBUF
Bus Free Time Between a
STOP and START
Condition
1.3
μs
tHD:STA
Hold Time (Repeated)
2
START Condition
0.6
μs
tLOW
LOW Period of SCL Clock
1.3
μs
tHIGH
HIGH Period of SCL Clock
0.6
μs
tSU:STA
Setup Time for a Repeated
START Condition
0.6
μs
tHD:DAT
Data Hold Time
tSU:DAT
Data Setup Time
tR
Rise Time of Both SDA and
SCL Signals
20 +
0.1CB
300
ns
tF
Fall Time of Both SDA and
SCL Signals
20 +
0.1CB
300
ns
tSU:STO
Setup Time for STOP
Condition
0.6
CB
Capacitive Load for Each
Bus Line
CI/O
I/O Capacitance (SDA,
SCL)
3
0
4
100
CB — total capacitance of one bus line in pF
0.9
μs
ns
μs
400
pF
10
pF
1. Specification is guaranteed by design and is not tested in production. VEN = 1.65V to VBAT.
2. After this period the first clock pulse is generated.
3. A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the VIHMIN of the SCLK signal) to bridge the
undefined region of the falling edge of SCLK.
4. A fast-mode device can be used in a standard-mode system, but the requirement tSU:DAT = to 250ns must then be met. This is automatically the case if the device does not stretch the LOW period of the SCLK signal. If such a device does stretch the LOW period of the
SCLK signal, it must output the next data bit to the SDA line tR max + tSU:DAT = 1000 + 250 = 1250ns before the SCLK line is released.
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AS3668
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6.2 Timing Diagrams
Figure 3. I2C Mode Timing Diagram
SDA
tBUF
tLOW
tR
tHD:STA
tF
SCLK
tHD:STA
tSU:STA
tHD:DAT
tHIGH
tSU:DAT
REPEATED
START
STOP START
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tSU:STO
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AS3668 2V0
Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7 Typical Operating Characteristics
VBAT = 3.6V, CBAT = CVCPOUT = 1μF, CFLY = 470nF, TAMB = -30ºC to +85ºC, typical values @ TAMB = +25ºC (unless
otherwise specified).
Figure 4. Off Mode Current vs. VBAT
Figure 5. CURRx linearity (0mA - 25.5mA) vs. Code
25
20
ICURRx [mA]
IBAT [µA]
0,4
0,2
15
10
5
Off Mode Current
0
0
2,7
3,1
3,5
3,9
4,3
4,7
5,1
0
5,5
VBAT [V]
100
200
Register CURRx current [DEC]
Figure 6. Output Voltage vs. load current (1:1, 4.2V,3,6V, 3,3V) L
Figure 7. Output voltage. vs. load current (1:2, 4.2V,3,6V, 3,3V)
5,3
5
4
VCP[V]
VCP[V]
5,2
3
2
5,1
1
VBAT = 3.6V
VBAT = 3.6V
VBAT = 3.3V
VBAT = 3.3V
VBAT = 4.2V
VBAT = 4.2V
5
0
0
10
20
30
40
0
50
10
20
100
100
90
90
80
80
70
70
60
50
40
30
60mA Load
50
60
50
40
30
60mA Load
20
30mA Load
10
40
Figure 9. CP Efficiency vs. VBAT in 1:1 Mode(10mA,30mA,60mA)
Efficiency [%]
Efficiency [%]
Figure 8. CP Efficiency vs.VBAT in 1:2 MODE(10mA,30mA,60mA)
20
30
ILOAD [mA]
ILOAD [mA]
30mA Load
10
10mA Load
0
10mA Load
0
2,7
3,1
3,5
3,9
4,3
VBAT [V]
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2,7
3,1
3,5
3,9
4,3
VBAT [V]
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AS3668 2V0
Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
ICURRx
VCP
50mV/Div
Figure 11. VCP and VBAT in 1:2 Mode and 50mA load current
1.3mA/Div
Figure 10. CURRx logarithmic PWM Ramp
500ms/Div
1μs/Div
Figure 13. Line Regulation autom. gain change to 1:2 mode with
1mA load current
2.5V
1μs/Div
10ms/Div
5.2V
VCP
4.8V
Figure 15. Line Regulation autom. gain change to 1:2 mode with
25.5mA load current
VCP
Figure 14. Line Regulation autom. gain change to 1:2 mode with
10mA load current
4V
1V/Div
3V
VBAT
2.5V
VBAT
1V/Div
3.5V
10ms/Div
10ms/Div
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VCP
3.5V
1V/Div
VCP
20mV/Div
5V
VBAT
Figure 12. VCP with charge pump in 1:2 mode and 10mA load
current
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AS3668 2V0
Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
Figure 17. Output current of CURRx vs. U(CURRx) with 10mA
CURRx output current
0
0
-10
-5
CURRx [mA]
CURRx [mA]
Figure 16. Output current of CURRx vs. U(CURRx) with 25,5mA
CURRx output current
-20
-10
-15
-30
0
0,5
1
1,5
0
2
0,5
1
1,5
2
UCURRx [V]
UCURRx [V]
Figure 18. Output current of CURRx vs. U(CURRx) with 1mA
CURRx output current)
Figure 19. Battery Current vs. VBAT with CP in 1:2 Mode (10mA,
30mA, 60mA
0
140
10mA CP load
30mA CP load
120
IVBAT [mA]
CURRx [mA]
60mA CP load
-0,5
100
80
60
-1
40
20
0
-1,5
0
0,5
1
1,5
2,5
2
3,5
Figure 20. CP efficiency vs. VBAT with automatic CP mode
switching
5,5
Figure 21. CP efficiency vs. ILOAD with automatic CP mode
switching
100
100
90
90
80
80
70
70
Efficiency [%]
Efficiency [%]
4,5
VBAT [V]
UCURRx [V]
60
50
40
30
60mA Load
20
60
50
40
30
Vbat = 3.0V
20
Vbat = 3.3V
30mA Load
10
10
10mA Load
Vbat = 3.6V
0
0
2,7
3,1
3,5
3,9
4,3
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0
10
20
30
40
50
ILOAD [mA]
VBAT [V]
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AS3668
Data Sheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
8.1 Charge Pump
The Charge Pump uses the external flying capacitor CFLY to generate output voltages higher than the battery voltage. There are two different
operating modes of the charge pump itself:
1:1 Bypass Mode
- Battery input and output are connected by a low-impedance switch
- battery current = output current.
1:2 Mode
- The output voltage is up to 2 times the battery voltage (without load), but is limited to VCPOUTmax all the time
- battery current = 2 times output current
Figure 22. Charge Pump Block Diagram .
As the battery voltage decreases, the Charge Pump must be switched from 1:1 mode to 1:2 mode in order to provide enough supply for the
current sinks. Depending on the actual current the mode with best overall efficiency can be automatically or manually selected:
The charge pump mode switching can be done manually or automatically with the following possible software settings:
Automatic
- Start with 1:1 mode
- Switch up automatically to 1:2 mode
Manual
- Set modes 1:1 and 1:2 by software
The Charge Pump requires the external components listed in the following table:
Table 5. Charge Pump External Components
Symbol
Parameter
Condition
CFLY
External Flying Capacitor
Ceramic low-ESR capacitor between pins CP and CN
CVCPOUT
Min
External Storage Capacitor Ceramic low-ESR capacitor between pins VCP and VSS
Typ
Max
Unit
470
nF
1.0
μF
Note: The connections of the external capacitors CVCPOUT and CFLY should be kept as short as possible.
.
Table 6. Charge Pump Characteristics
Symbol
Parameter
Condition
Min
ICPOUT
Output Current
Continuous
Depending on PCB layout
0.0
VCPOUTmax
Output Voltage
Internally limited, Including output ripple

Efficiency
Including current sink loss;
ICPOUT = 60mA.
88
%
ICP1_2
Power Consumption
without Load,
fclk = 1 MHz
1:2 Mode
2.5
mA
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Typ
Max
Unit
60
mA
5.6
V
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AS3668
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 6. Charge Pump Characteristics
Symbol
Parameter
Condition
Rcp1_1
1:1 Mode; VBAT 3.6V
2.5
Rcp1_2
Effective Charge Pump
Output Resistance (Open
Loop, fclk = 1MHz)
1:2 Mode; VBAT  3V
20
fclk Accuracy
Accuracy of Clock
Frequency
Vcurr_source
LED1 - CURR4 current
source dropout voltage
Isoft_start
Current limit for soft start
feature
tdeb
CP automatic upswitching debounce time
8.1.1
Min
Typ
-10
If the voltage drops below this threshold, the charge
pump will use the next available mode
(1:1 -> 1:2)
Max
Unit

10
%
0.2
V
400
mA
cp_start_debounce=0
32
ms
cp_start_debounce=1
200
μs
Charge Pump Mode Switching
If automatic mode switching is enabled the charge pump monitors the current sources, which are directly connected to the output of the charge
pump VCP. In order to identify the enabled current sources, the related registers should be setup before starting the charge pump. If any of the
voltage on these current sources drops below the threshold (Vcurr_source), the higher mode is selected after the debounce time (tdeb).
The charge pump mode switching supports only a mode change to a higher charge pump mode (e.g.: mode 1:1 to mode 1:2). In case VBAT
increases again during operation the automatic mode switching will not change the operation mode from 1:2 down to 1:1. In order to change the
mode all current sources must be switched off to reset the charge pump mode switching mechanism. After enabling the current sources again
the mode switching mechanism chooses the appropriate mode for the optimized operation of the charge pump either in 1:1 mode or 1:2 mode. In
case an automatic pattern is used the current sources get a reset after each pattern cycle because the current sources are automatically
switched off when executing a pattern after each cycle.
Figure 23. Charge Pump Mode Switching .
8.1.2
Soft Start
An implemented soft start mechanism reduces the inrush current. Battery current is smoothed when switching the charge pump on and also at
each switching condition. This precaution reduces electromagnetic radiation significantly.
8.1.3
Unused Charge Pump
If the charge pump is not used, capacitors CFLY and CVCPOUT can be removed. The pins CP, CN and VCP should be left open and keep
register cp_on and cp_auto_on at 0 (default value).
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8.1.4
Charge Pump Control Register .
Table 7. Reg Control Register
0x00 Reg Control register
Bit
Bit Name
2
cp_on
Default
0
Access
Bit Description
R/W
This bit enables the charge pump for operation if at lease one current source
is enabled and the current source has a low voltage condition. Once the
charge pump is running it will be keep on even if all current sources are
switched off.
0: Chargepump off
1: Charge Pump on
Table 8. CP Control Register
0x23 Current Control Register
Bit
Bit Name
6
cp_auto_on
5
4
Default
Access
Bit Description
1
R/W
This bit enables the charge pump for operation. Once at last one current
source is enabled and minimum one current source has a low voltage
condition the charge pump is switched on. If all current sources are switched
off again the charge will also switch of automatically.
0: Chargepump off
1: Chargepump on in automatic mode
0
R/W
Selects the startup debounce time of the charge pump
0: 32ms debounce time.
1: 240μs debounce time
R/W
Allows the user to select between automatic mode switching or manual
mode switching of the charge pump. If the bit is set, the user can change
register cp_mode in order to select 1:1 mode or 1:2 mode of the charge
pump.
0: Automatic CP Mode Switching
1: Manual CP Mode Switching using register cp_mode
0
R/W
Selects the charge pump operating mode if register cp_mode_switching is
set to 1. Reading the register return the mode in which the charge pump is
operating, either 1:1 or 1:2 mode.
0: 1:1 mode
1: 1:2 mode
0
R/W
Selects the charge pump clock frequency.
0: 1Mhz
1: 500kHz
cp_start_debounce
cp_mode_switching
0
2
cp_mode
0
cp_clk
8.2 Current Sources
The AS3668 features four general purpose current sources. All current sources and be controlled independently from each other and share
internally the same power supply VCP.
Table 9. Current Sink Function Overview
Current Sink
Resolution
Max. Voltage
(V)
Max. Current
(mA)
(Bits)
(mA)
Software Current
Control
Hardware On/Off Control
5.5
25.5
8
0.1
Separate for each
current source
Internal PWM; external
PWM at GPIO/AUDIO_IN,
Pattern generator
CURR1
CURR2
CURR3
CURR4
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.
Table 10. Current Sources Characteristiks
Symbol
Parameter
Condition
Min
IBIT7
Current sink if Bit7 = 1
12.8
IBIT6
Current sink if Bit6 = 1
6.4
IBIT5
Current sink if Bit5 = 1
3.2
IBIT4
Current sink if Bit4 = 1
IBIT3
Current sink if Bit3 = 1
IBIT2
Current sink if Bit2 = 1
0.4
IBIT1
Current sink if Bit1 = 1
0.2
IBIT0
Current sink if Bit0 = 1
0.1
IMATCH
Matching Accuracy
IOUT
VCUR1-4
Max
1.6
CURR1, CURR2, CURR3, CURR4 > 0.2V
CURR1, CURR2, CURR3 and CURR4
Typ
Unit
mA
0.8
-10
+10
%
Absolute Accuracy
-15
+15
%
Voltage Compliance
0
VCP-0.2
V
Figure 24. Internal processing of current sources
8.2.1
Unused Current Sources
Unused current sources can be left open. There are no external connections or components necessary if they are not used.
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8.2.2
Current Source Registers .
Table 11. Current Control Register
0x01 Current Control Register
Bit
Bit Name
7:6
curr4_mode
Default
0
5:4
1:0
R/W
R/W
00: Current Source CURR3 is in off mode
01: Current Source CURR3 is in on mode
10: Current source CURR3 is in PWM control mode
11: Current source CURR3 is in LED pattern generation mode
R/W
00: Current Source CURR2 is in off mode
01: Current Source CURR2 is in on mode
10: Current source CURR2 is in PWM control mode
11: Current source CURR2 is in LED pattern generation mode
R/W
00: Current Source CURR1 is in off mode
01: Current Source CURR1 is in on mode
10: Current source CURR1 is in PWM control mode
11: Current source CURR1 is in LED pattern generation mode
curr2_mode
0
curr1_mode
3
Bit Description
00: Current Source CURR4 is in off mode
01: Current Source CURR4 is in on mode
10: Current source CURR4 is in PWM control mode
11: Current source CURR4 is in LED pattern generation mode
curr3_mode
0
3:2
Access
Table 12. Current Source Register LED1
0x02 Current Control Register
Bit
Bit Name
7:0
curr1_current
Default
0x40
Access
R/W
Bit Description
0000 0000: 0mA current output from source CURR1
0000 0001: 0.1mA current output from source CURR1
0000 0010: 0.2mA current output from source CURR1
0000 0011: 0.3mA current output from source CURR1
...
1111 1111: 25.5mA current output from source CURR1
Table 13. Current Control Register LED2
0x03 Current Control Register
Bit
Bit Name
7:0
curr2_current
Default
0
Access
R/W
Bit Description
0000 0000: 0mA current output from source CURR2
0000 0001: 0.1mA current output from source CURR2
0000 0010: 0.2mA current output from source CURR2
0000 0011: 0.3mA current output from source CURR2
...
1111 1111: 25.5mA current output from source CURR2
Table 14. Current Control Register CURR3
0x04 Current Control Register
Bit
Bit Name
7:0
curr3_current
Default
0
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Access
R/W
Bit Description
0000 0000: 0mA current output from source CURR3
0000 0001: 0.1mA current output from source CURR3
0000 0010: 0.2mA current output from source CURR3
0000 0011: 0.3mA current output from source CURR3
...
1111 1111: 25.5mA current output from source CURR3
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Table 15. Current Control Register CURR4
0x05 Current Control Register
Bit
Bit Name
7:0
curr4_current
Default
0
Access
R/W
Bit Description
0000 0000: 0mA current output from source CURR4
0000 0001: 0.1mA current output from source CURR4
0000 0010: 0.2mA current output from source CURR4
0000 0011: 0.3mA current output from source CURR4
...
1111 1111: 25.5mA current output from source CURR4
Table 16. CURRx Low Voltage Status Register
0x2b Current Source Low Voltage Status Register
Bit
Bit Name
3
curr4_low_v
Default
0
2
0
R
R
This is a read only register and returns 0 if the voltage on current source
CURR3 is ok. If the voltage drops below 200mV across the current source
the bit is set to 1.
0: CURR3 voltage is OK
1: CURR3 voltage is too low
R
This is a read only register and returns 0 if the voltage on current source
CURR2 is ok. If the voltage drops below 200mV across the current source
the bit is set to 1.
0: CURR2 voltage is OK
1: CURR2 voltage is too low
R
This is a read only register and returns 0 if the voltage on current source
CURR1 is ok. If the voltage drops below 200mV across the current source
the bit is set to 1.
0: CURR1 voltage is OK
1: CURR1 voltage is too low
curr2_low_v
0
curr1_low_v
0
Bit Description
This is a read only register and returns 0 if the voltage on current source
CURR4 is ok. If the voltage drops below 200mV across the current source
the bit is set to 1.
0: CURR4 voltage is OK
1: CURR4 voltage is too low
curr3_low_v
0
1
Access
8.3 Power - On Reset
The AS3668 provides an power - on reset feature that is controlled by two different sources:
VBAT supply voltage
Serial interface state (SCL only)
If the internal VBAT supply voltage reset is forced, when the supply voltage VBAT of AS3668 drops below a predefined voltage, the device enters
shutdown mode. This predefined voltage is 2V (typ.) and is defined as VPOR_VBAT. Besides this hard wired voltage level where an internal reset
is forced to shut down the device, AS3668 supports an additional VBAT monitoring feature. This means that the designer can select according to
its application requirements a reset level which is appropriate for mobile Li-Ion battery powered applications. The use case for this second VBAT
monitoring is to make sure that if a mobile device switches off suddenly, at a dedicated voltage, to make sure that also AS3668 enters power
down mode. Otherwise unwanted LED effects could occur even if the digital system is not running any more. AS3668 allows the designer now to
set the VBAT monitoring level to the same voltage level the whole system is powering down. There’s no need any more for the CPU to reset or
power down AS3668 in a low battery case any more. The device can handle this use case automatically.
In addition to the VBAT voltage monitoring the device supports also a shut down function forced by the serial interface. If the voltage on the serial
interface pin SCL is below 1V (typ.) and GPIO/AUDIO_IN pin is low, the device forces a reset. To prevent the system against wrong resets
caused by electromagnetically influences there is also a debounce timer integrated with a typical debounce time of 100ms. This debounce time
is used for VBAT monitoring as well. If the serial interface monitoring is not supposed to be used in an application it is also possible to disable the
feature using the corresponding register bit.
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Figure 25. Reset Circuit Block Diagram
Table 17. Power On Reset Parameters
Symbol
Parameter
Condition
VPOR_VBAT
Overall Power-On Reset
Monitor voltage on VBAT; power-on reset for all
internal functions.
VMON_VBAT
Register defined stand by
mode voltage
depending on register setting the voltage can be
configured
VPOR_PERI
Reset Level for pins SCL
Monitor voltage on pin SCL
tPOR_DEB
Reset debounce time for
pins SCL
tstart
Interface Startup Time
Min
Typ
Max
2.0
3.0V
V
3.3V
1.0
110
Unit
130
3
V
150
ms
ms
8.4 VBAT Monitor
The VBAT monitor is a supervisory circuit. The monitor is per default disabled when the AS3668 is powered up. The function can be used in order
to send the device automatically into standby mode if the supply voltage of AS3668 drops below the defined values in register vmon_vbat. All
together the user can select between three different voltage thresholds for this function with 3.375V, 3.3V and 3.0V. If the function is disabled the
device switches of if the battery voltage drops below 2.0V. The monitor function has also a debouncer with 100ms implemented in order to filter
the 217Hz GSM noise pulses from the battery supply voltage. Without the debouncer the chip would be susceptible to this noise and maybe
enter into standby mode due to a misinterpretation of the supply voltage.
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Figure 26. VBAT Monitor Block Diagram
Table 18. VBAT Monitor Parameters
Symbol
Parameter
Condition
Min
VMON_VBAT
Register defined stand by
mode voltage
depending on register setting the voltage can be
configured
3.0V
8.4.1
Typ
Max
Unit
3.3V
VBAT Monitor Registers .
Table 19. Overtemperature Control / VBAT Monitor Register
0x29 Overtemperature Control / VBAT Monitor Register
Bit
Bit Name
6:5
vmon_vbat
Default
R/W
1
R/W
This bit allows the user to disable the I2C shutdown feature. If the bit is set to
‘0’ both I2C signal lines can be low without shutting down AS3668.
0: disables the automatic shutdown of AS3668
1: enables the automatic shutdown of AS3668
0
W
This register is a self clearing register. Write a ‘1’ to this register to clear
ov_temp.
R
This is a read only register and provides feedback about the junction
temperature of the chip. The bit is usually set if the junction temperature
reaches about 140°C.
0: Junction temperature OK
1: Junction Overtemperature
shutdown_enable
2
rst_ov_temp
1
ov_temp
0
0
Bit Description
0: Device enters shutdown mode if VBAT voltage drops below ~2.0V
1: Device enters standby mode if VBAT voltage drops below 3.0V
2: Device enters standby mode if VBAT voltage drops below 3.15V
3:Device enters standby mode if VBAT voltage drops below 3.3V
0
4
Access
ov_temp_on
1
R/W
This bit allows the user the enable/disable the junction temperature
monitoring for AS3668.
0: Temperature supervision OFF
1: Temperature supervision ON
8.5 Temperature Supervision
An integrated temperature sensor provides over-temperature protection for the AS3668. This sensor generates a flag if the device temperature
reaches the over temperature threshold of 140º. The threshold has a hysteresis to prevent oscillation effects.
If the device temperature exceeds the T140 threshold all current sources and the charge pump get disabled and the ov_temp flag is set. After
decreasing the temperature by THYST operation is resumed. Although the device resumes ordinary operation after a overtemperature event, the
register ov_temp keeps set to 1. Even a read operation from the register doesn’t reset the register. Therefore it’s necessary to use the register
rst_ov_temp to reset the overtemperature register ov_temp.
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The ov_temp flag can only be reset by first writing a 1 to the register bit rst_ov_temp. If bit ov_temp_on = 1 activates temperature supervision
Table 20. It is recommend to leave this bit set (default state).
Table 20. Overtemperature Detection
Symbol
Parameter
Condition
Min
Typ
Max
Unit
T140
ov_temp Rising Threshold
140
ºC
THYST
ov_temp Hysteresis
5
ºC
Table 21. Overtemperature Control / VBAT Monitor Register
0x29 Overtemerature Control / VBAT Monitor Register
Bit
Bit Name
Default
Access
Bit Description
2
rst_ov_temp
0
W
Write a 1 to this register to reset ov_temp
1
ov_temp
0
R
0: Junction temperature is ok and below T140
1: Junction temperature is too high and above T140
0
ov_temp_on
1
R/W
0: Disables the overtemperature supervision (not recommended)
1: Enabled the overtemperature supervision
8.6 I²C Serial Interface Bus
The AS3668 supports the I²C serial bus and data transmission protocol in fast mode at 400kHz. The AS3668 operates as a slave on the I²C bus.
Due to the reason that the device is also power up/down with the I²C interface there is a debouncer (130ms) on the signal lines integrated to
avoid a system shut down while having I²C traffic on the bus.
Figure 27. Serial Interface Block Diagram
The bus must be controlled by a master device that generates the serial clock (SCL), controls the bus access, and generates the START and
STOP conditions. Connections to the bus are made via the open-drain I/O pins SCL and SDA. The clock line SCL is never held low by AS3668
because clock stretching of the bus is not supported.
Figure 28. AS3668 Interface Initialization
1
8
9
1
8
9
SCLK
SDA
0
0
0
0
0
X
X
R/W
D15 D14 D13 D12 D11 D10
D9
D8
I2C register address has not been defined yet.
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Figure 29. Bus Protocol
MSB
SDI
ACK from
Receiver
Slave Address
R/W
Direction Bit
ACK from
Receiver
1
SCLK
2
6
7
8
9
ACK
START
1
2
3-8
8
9
ACK
Repeat if More Bytes Transferred
STOP or
Repeated
START
The bus protocol (as shown in Figure 29) is defined as:
- Data transfer may be initiated only when the bus is not busy.
- During data transfer, the data line must remain stable whenever the clock line is HIGH. Changes in the data line while the clock line is
HIGH will be interpreted as control signals.
The bus conditions are defined as:
-
Bus Not Busy. Data and clock lines remain HIGH.
Start Data Transfer. A change in the state of the data line, from HIGH to LOW, while the clock is HIGH, defines a START condition.
Stop Data Transfer. A change in the state of the data line, from LOW to HIGH, while the clock line is HIGH, defines the STOP condition.
Data Valid. The state of the data line represents valid data, when, after a START condition, the data line is stable for the duration of the
HIGH period of the clock signal. There is one clock pulse per bit of data.
Each data transfer is initiated with a START condition and terminated with a STOP condition. The number of data bytes transferred
between START and STOP conditions is not limited and is determined by the master device. The information is transferred byte-wise and
each receiver acknowledges with a ninth-bit.
Within the I²C bus specifications a high-speed mode (3.4MHz clock rate) is defined.
- Acknowledge: Each receiving device, when addressed, is obliged to generate an acknowledge after the reception of each byte. The master device must generate an extra clock pulse that is associated with this acknowledge bit. A device that acknowledges must pull down the
SDA line during the acknowledge clock pulse in such a way that the SDA line is stable LOW during the HIGH period of the acknowledge
clock pulse. Of course, setup and hold times must be taken into account. A master must signal an end of data to the slave by not generating an acknowledge bit on the last byte that has been clocked out of the slave. In this case, the slave must leave the data line HIGH to
enable the master to generate the STOP condition.
- Figure 29 on page 23 details how data transfer is accomplished on the I²C bus. Depending upon the state of the R/W bit, two types of
data transfer are possible:
- Master Transmitter to Slave Receiver. The first byte transmitted by the master is the slave address, followed by a number of data bytes.
The slave returns an acknowledge bit after the slave address and each received byte.
- Slave Transmitter to Master Receiver. The first byte, the slave address, is transmitted by the master. The slave then returns an acknowledge bit. Next, a number of data bytes are transmitted by the slave to the master. The master returns an acknowledge bit after all received
bytes other than the last byte. At the end of the last received byte, a not-acknowledge is returned. The master device generates all of the
serial clock pulses and the START and STOP conditions. A transfer is ended with a STOP condition or a repeated START condition. Since
a repeated START condition is also the beginning of the next serial transfer, the bus will not be released.
The AS3668 can operate in the following slave modes:
- Slave Receiver Mode. Serial data and clock are received through SDA and SCL. After each byte is received, an acknowledge bit is transmitted. START and STOP conditions are recognized as the beginning and end of a serial transfer. Address recognition is performed by
hardware after reception of the slave address and direction bit.
- Slave Transmitter Mode. The first byte (the slave address) is received and handled as in the slave receiver mode. However, in this mode
the direction bit will indicate that the transfer direction is reversed. Serial data is transmitted on SDA by the AS3668 while the serial clock
is input on SCL. START and STOP conditions are recognized as the beginning and end of a serial transfer.
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8.6.1
I²C Device Address Byte
The address byte (see Figure 30) is the first byte received following the START condition from the master device. The 7 bit device address is
0x42.
Figure 30. I²C Device Address Byte
address:
MSB
6
5
4
3
2
1
LSB
1
0
0
0
0
AD1
AD0
R/W
- Bit 1 and bit 2 of the address byte are defined by the external bus connection of the slave to the master shown in chapter 8.6.3. A maximum of two devices can be connected in parallel on the same bus at one time.
- The last bit of the address byte (R/W) define the operation to be performed. When set to a 1 a read operation is selected; when set to a 0
a write operation is selected.
Following the START condition, the AS3668 monitors the I²C bus, checking the device type identifier being transmitted. Upon receiving the
address code, and the R/W bit, the slave device outputs an acknowledge signal on the SDA line.
8.6.2
Command Byte
The AS3668 operation, (see Table 29 on page 23) is determined by a command byte (see Table 31).
Figure 31. Command Byte
MSB
6
5
4
3
2
1
LSB
A7
A6
A5
A4
A3
A2
A1
A0
Figure 32. Command and Single Data Byte received by AS3668
From Master to Slave
AS3668 Registers
From Slave to Master
S
0
Slave Address
A7
A6
R/W A
A5
A4
A3
A2
A1
A0
D7
D6
A
Command Byte
D5
D4
D3
D2
D1
D0
A
Data Byte
P
1 Byte
Acknowledge
from AS3668
Acknowledge
from AS3668
0
Acknowledge
from AS3668
0
0
Autoincrement
Memory Word
Address
Figure 33. Setting the Pointer to a Address Register to select a Data Register for a Read Operation
From Master to Slave
AS3668 Registers
From Slave to Master
S
0
Slave Address
R/W A
Acknowledge
from AS3668
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A7
0
A6
A5
A4
A3
A2
A1
A0
Command Byte
Acknowledge
from AS3668
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Figure 34. Reading n Bytes from AS3668
Autoincrement
Memory Word
Address
From Master to Slave
From Slave to Master
S
Acknowledge
from AS3668
Slave Address
Acknowledge
from Master
0
R/W A
1
D6
D5
D4
D3
D2
D1
AS3668 Registers
8.6.3
Not Acknowledge
from Master
0
1
n Bytes
A
First Data Byte
D7
Stop reading
D0
/A
Second Data Byte
D7
D6
D5
D4
D3
D2
D1
P
D0
Autoincrement
to next address
I²C Device Address Selection
The AS3668 features two I²C slave addresses without having a dedicated address selection pin. The selection of the I²C address is done with
the interconnection of AS3668 to the bus lines shown in Figure 35 below. The serial interface logic inside AS3668 is able to distinguish between
a direct I2C connection to the master or a second option where data and clock line are crossed. Therefore it is only possible to address a
maximum of two AS3668 slaves on one I²C bus.
Figure 35. I²C Address Selection Application Diagram
DEVICE 1
DEVICE 2
The I²C addresses for the devices in the different connection modes can be found in Table 22.
Table 22. I²C Addresses for AS3668
DEVICE Number
7 bit I²C address
8 Bit read address
8 Bit write address
1(default)
0x42
0x85
0x84
2
0x43
0x87
0x86
8.7 Operating Modes
Due to the reason that AS3668 has no dedicated enable or power - on pin the device is basically controlled with the I²C signal lines SDA and
SCL. If the voltages on these pins are less than VPOR_PERI for > tPOR_DEB and GPIO/AUDIO_IN input is low, the AS3668 is in shut down
mode with a minimized current consumption of IVBAT = 1μA (typ.). All blocks inside AS3668 are basically switched off except the power up reset
circuit is always active.
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If the voltage on the I²C signal lines is bigger than VPOR_PERI for a time frame longer than tPOR_DEB, the device changes it’s operation mode
from power off to standby mode. In this use state only the power on reset and the I²C block of the device is active with an average current
consumption of 10μA(typ.). The device changes its operating mode from standby to active mode automatically if one of the following blocks
inside AS3668 are activated:
Charge Pump
Current Source
Pattern Mode activated
External PWM mode via GPIO/AUDIO_IN
In addition to the I²C monitoring for startup of the device it is possible to power up AS3668 with GPIO/AUDIO_IN pin while the I²C signal lines are
low. this is a special use case which starts a predefined pattern on current source CURR1. For a detailed description please refer to chapter
8.7.1.
Besides the monitoring of the I²C signal lines there is also an additional feature which monitors the battery supply voltage VBAT. Basically there
are two voltage levels where this voltage monitoring becomes active. The first voltage VPOR_VBAT can be seen as a shut down and minimum
supply voltage of the device voltage which is fixed at 2V (typ.). The same voltage level is used for the power on reset circuit. If the battery voltage
drops below VPOR_VBAT the device automatically changes from active mode or standby mode to off mode. Besides the VPOR_VBAT level there
is a second VBAT monitoring voltage which can be activated in a register. This voltage VMON_VBAT is typically set to 3.4V (default register
setting) but can be reconfigured using the I²C interface down to 2.4V according to the requirements of an application. It is also possible to disable
the VBAT monitoring. The VPOR_VBAT monitoring can not be disabled.
Table 23. Truth Table for AS3668 operating modes
AS3668 Blocks
Off Mode
Standby Mode
Active Mode
Power On/Off Reset
enabled
enabled
enabled
I²C
disabled
enabled
enabled
Charge Pump
disabled
disabled
enabled/disabled depending on
register setting
Current Sources
disabled
disabled
enabled/disabled depending on
register setting
Pattern Mode
disabled
disabled
enabled/disabled depending on
register setting
External PWM
disabled
disabled
enabled/disabled depending on
register setting
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Figure 36. Startup and operating mode selection
8.7.1
GPIO/AUDIO_IN Automatic Pattern Start-up Mode
As described in the previous chapter it is basically possible to start up the device using the I²C clock line. In some cases it is not possible to
configure AS3668 in an application because the application processor is not running that time. Therefore AS3668 supports a special startup
mode shown in Figure 36 and Figure 37 to start up the device without pulling the I²C clock line high. If an external device is connected to the
GPIO/AUDIO_IN pin of AS3668 and the pin is pulled high the device starts up with an default pattern running on CURR1 although the I²C clock
line is low shown in Figure 37. If for example AS3668 starts up with I²C and the GPIO/AUDIO_IN pin is low that time the device starts up in
standby mode and can be configured using the two wire interface. If the I2C signal lines become low whereas the GPIO/AUDIO_IN pin is high at
the same time the chip keeps activated and running as long as GPIO/AUDIO_IN pin is high. Once the GPIO/AUDIO_IN pin goes low the device
enters shut down mode. This use case enables the user to keep on charging the battery for example and indicate this with a special PWM
pattern while the CPU is powered down for example. A typical application is shown in Figure 38.
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Figure 37. Timing Diagram Startup Modes
Figure 38. Typical Application Automatic Pattern Startup
The application in Figure 38 shows the AS3668 connected to a CPU and a typical charger. Most of the stand alone chargers do have a open
drain output for charger indication with a LED. This output pin can be used to control AS3668. If the charger is active the GPIO/AUDIO_IN input
pin of AS3668 is pulled high. The chip starts up with a default pattern on CURR1output. With this special mode it is possible to indicate charging
using for example the RGB LED connected to AS3668 although the CPU is not running. This use case can happen if the battery of a device is
almost fully discharged and the CPU can not start up because the battery voltage is too low in trickle charge mode. The automatic pattern startup mode allows the operate the LED on AS3668 without I²C interaction with the CPU. AS3668 starts up in automatic pattern start-up mode with
the default pattern shown in Figure 39. Please mind that the pattern is only active for current source CURR1.
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Figure 39. Timing for Automatic Pattern Startup
Table 24. Automatic Pattern Start-Up Parameters
Symbol
Parameter
Condition
Min
Typ
Max
Unit
tr_CURR
Rise time for dimming up
CURR1
2.62
s
tf_CURR
Fall time for dimming down
CURR1
2.62
s
ton_CURR
On time for CURR1
49
ms
toff_CURR
Off time for CURR1
0.54
s
ICURR1
Output Current for CURR1
6.4
mA
8.8 General Purpose Input / Output
The pin GPIO/AUDIO_IN is a general purpose input / output which is shared as a audio input for music synchronization. The pin can support the
following features:
Digital Schmitt Trigger Input
Digital output with open drain functionality
Analogue Audio input for audio controlled LEDs
PWM input for CURR1, CURR2, CURR3 and CURR4 (max. 1MHz)
Device Start-up in Automatic Pattern Generation mode
Figure 40. General Purpose Input / Output Block diagram
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Although the GPIO/AUDIO_IN pin supports digital output as well for simple control exercises an external pull up resistor is mandatory. The pin is
not able to actively drive the signal line because there is no push/pull stage integrated. The internal pull down resistor is disabled in audio
synchronization mode.
For a detailed description of music playback synchronization please refer to chapter 8.9.
8.8.1
Unused General Purpose Input / Output
If the pin is not used it is recommended to connect it to ground.
8.8.2
GPIO Control Register .
.
Table 25. GPIO Control Register
0x06 GPIO Control Register
Bit
Bit Name
2
gpio_in_invert
1
gpio_in_en
0
gpio_mode
Default
Access
Bit Description
0
R/W
This bit allows the user to invert input signal of GPIO/AUDIO_IN if the pin is
configured as digital input.
0: Non-inverted digital input GPIO/AUDIO_IN
1: Inverted digital input GPIO/AUDIO_IN
1
R/W
0: GPIO/AUDIO_IN pin is configured as analog input (audio mode)
1: GPIO/AUDIO_IN pin is configured as digital input (general purpose)
0
R/W
0: GPIO/AUDIO_IN pin is configured as input
1: GPIO/AUDIO_IN pin is configured as output in open drain configuration
The pin requires an external pull up resistor
Table 26. GPIO Signal Register
0x08 GPIO Signal Register
Bit
Bit Name
0
gpio_in
Default
0
Access
R
Bit Description
The register is a read only register. The register is set to 1, if the pin GPIO/
AUDIO_IN is externally pulled high. The register is set to 0, if the pin is
connected to ground.
Table 27. GPIO Output Register
0x07 GPIO Output Register
Bit
Bit Name
0
gpio_out
Default
0
Access
Bit Description
R/W
This register is the output register if the pin GPIO/AUDIO_IN is configured as
output. Writing to the register changes the output state of the pin.
0: GPIO/AUDIO_IN pin low
1: GPIO/AUDIO_IN pin high (external pull-up resistor required)
8.9 Audio Input
The audio input pin GPIO/AUDIO_IN is shared with a general purpose input/output. It is possible to switch the operating mode of the pin from a
GPIO to an analogue audio input. This multiplexed audio input pin allows the AS3668 to do lighting effects depending on the audio content
connected to GPIO/AUDIO_IN.
The block diagram for the signal processing path is shown in Figure 41. The analogue audio signal is coupled into the pin GPIO/AUDIO_IN with
an external DC blocking capacitor. The integrated audio pre-amplifier with automatic gain control attenuates or amplifies the input signal to avoid
clipping inside the signal processing path and furthermore increase the dynamic range of the signal in case a very small signal is applied to
AS3668. The AGC of the preamplifier uses the audio gain defined in register audio_gain as start value and changes the gain in a range of +/3dB. The pre-amplified audio signal is then feed into an special analogue signal processing unit to create special lighting effects. Various settings
inside the signal processing unit allow the user to define different types fancy lighting effects. This processing unit it directly linked together with
the control logic for the four current sources of the device. Thus, besides the ordinary lighting pattern control of the current sources with register
settings, the outputs are directly controlled in audio mode from the audio signal processing unit.
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Figure 41. Audio Input block diagram
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8.9.1 Audio Control Register . .
Table 28. Audio AGC Register
0x40 Audio AGC Register
Bit
Bit Name
6
agc_up_level
5
4:3
Default
Access
0
R/W
This bit allows the change of the AGC up switching threshold.
0: Default AGC up switching threshold
1: Increased AGC up switching threshold
0
R/W
This bit allows the change of the AGC down switching threshold.
0: Default AGC down switching threshold
1: Increased AGC down switching threshold
R/W
Defines the decay time for the automatic gain control of the audio input
amplifier for decreasing the gain.
00: 0.131s
01: 0.262s
10: 0.393s
11: 0.524s
R/W
Defines the decay time for the automatic gain control of the audio input
amplifier for increasing the gain.
00: 0.262s
01: 0.524s
10: 0.786s
11: 1.049s
R/W
This bit allows the user the enable / disable the automatic gain control of the
audio input amplifier.
0: Automatic Gain Control off
1: Automatic Gain Control on
agc_down_level
decay_agc_down
0
2:1
decay_agc_up
0
0
agc_on
0
Bit Description
Table 29. Audio Input Buffer Register
0x41 Audio Input Buffer Register
Bit
Bit Name
7
audio_dis_start
Default
0
6
R/W
R/W
Configures the input capacitor precharging mechanism for auto precharging
or manual precharging.
0: Automatic Precharging
1: Manual Precharging
R/W
Configures the gain of the audio preamplifier. The gain can be configured in
the range of -6dB up to +25dB according to the register setting in 1dB steps.
0 0000: -6dB
0 0001: -5dB
0 0010: -4dB
0 0011: -3dB
...
1 1111: 25dB
R/W
This bit switches the internal audio buffer amplifier on and off according to
the register setting
0: Audio Buffer off
1: Audio Buffer on
audio_gain
0
0
Bit Description
Enables the audio input capacitor precharging. This function is only active if
register audio_man_start is set to manual precharging. After precharging
register audio_dis_start must be cleared again.
0: Input capacitor precharging enabled
1: Input capacitor precharging disabled
audio_man_start
0
5:1
Access
aud_buf_on
0
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Table 30. Audio Control Register
0x42 Audio Control Register
Bit
Bit Name
7
audio_input_pin
Default
0
6
R/W
R/W
This bit defines if the internal pull down resistor of GPIO/AUDIO_IN pin is
enabled or disabled. If the audio mode is enabled the internal pull down is
automatically disabled
0: Pull down resistor enabled if register aud_buf_on is set to ‘0’
1: Pull down resistor disabled
adc_characteristic
0
Bit Description
This bit enables pin GPIO/AUDIO_IN or CURR4 pin to be configured as
audio input pin for audio playback synchronization of the current sources.
0: GPIO/AUDIO_IN selected for audio synchronization
1: CURR4 pin selected for audio synchronization
pld_off
0
5
Access
R/W
Defines the ADC characteristic of the ADC for general purpose ADC
measurements depending on the selected ADC characteristics in register
adc_mode.
00: x*250mV (adc_mode = 0)
01: x*50mV (adc_mode = 0)
x
00: 75mV*2 (adc_mode = 0 or adc_mode = 1)
4:3
audio_decay
0
2:0
R/W
Defines the audio decay time.
00: 10ms
01: 20ms
10: 40ms
11: 80ms
R/W
In this register it is possible to select between different audio synchronization
modes of the current sources in order to create different lighting effects.
000: 4 LED bar code
001: 4 LED bar code with dimming
010: Running LED bar code
011: Running LED bar code with dimming
100: RGB (CURR1, CURR2, CURR3; CURR4 not used)
101: RGB with dimming (CURR1, CURR2, CURR3; CURR4 not used)
110: 4 LED parallel with dimming
111: Do not use
audiosync_mode
0
Table 31. Audio Output Register
0x43 Audio Output Register
Bit
Bit Name
3
curr4_aud_en
Default
0
2
R/W
This register allows the user to select between normal control (e.g. PWM
pattern control) and audio synchronization mode of current source CURR4 .
0: CURR4 normal function
1: CURR4 audio synchronization mode
R/W
This register allows the user to select between normal control (e.g. PWM
pattern control) and audio synchronization mode of current source CURR3 .
0: CURR3 normal function
1: CURR3 audio synchronization mode
R/W
This register allows the user to select between normal control (e.g. PWM
pattern control) and audio synchronization mode of current source CURR2 .
0: CURR2 normal function
1: CURR2 audio synchronization mode
R/W
This register allows the user to select between normal control (e.g. PWM
pattern control) and audio synchronization mode of current source CURR1 .
0: CURR1 normal function
1: CURR1 audio synchronization mode
curr2_aud_en
0
0
Bit Description
curr3_aud_en
0
1
Access
curr1_aud_en
0
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8.10 LED Pattern Configuration
8.10.1 Single Pulse Mode
The AS3668 supports basically three basic LED pattern modes to create fancy lighting effect for the LEDs which can be connected to the current
sources CURR1, CURR2, CURR3 and CURR4. The first and basic mode is the “Single Pulse Mode”. This mode is basically defined out of five
parameters shown in Figure 42 below.
Figure 42. LED Pattern - Single Pulse Mode
The first parameter which can be configured in register pwm_dim_speed_up is tr_CURR. This time defines how long it takes to ramp up the
current to the defined value in registers curr1_current, curr2_current, curr3_current and curr4_current for each current source. The dimming of
the current source is of course logarithmic for a better visual effect but can be reconfigured to linear mode in register pwm_dim_shape. The
second parameter tf_CURR, which can be controlled in register pwm_dim_speed_down, defines the fall time for dimming down the LEDs. The
third parameter is ton_CURR and can be configured in register pattern_ton. It defines how long a current source keeps switched on with the
current configured in register curr1_current, curr2_current, curr3_current and curr4_current for each current source. Also this down dimming is
done with a logarithmic scale for a better visual effect. The last parameter toff_CURR defines how long the current sources or LEDs are switched
off until the whole pattern cycle starts from the beginning and can be configured in register pattern_toff.
Table 32. Singe Pulse Mode Parameters
Symbol
Parameter
tr_CURR
Rise time for dimming up
CURRx
tf_CURR
Condition
Min
Typ
Max
Unit
0
8.39
s
Fall time for dimming down
CURRx
0
8.39
s
ton_CURR
On time for CURRx
0.05
4.2
s
toff_CURR
Off time for CURRx
0.08
8.4
s
Please mind that the settings for tf_CURR, tr_CURR, ton_CURR and toff_CURR are valid for all four current sinks at the same time. It is not
possible to define individual time values for each current source differently to each other. The only parameter which can differ from on current
source to another is the current which can be configured in registers curr1_current, curr2_current, curr3_current and curr4_current for each
current source individually. An example how the mode looks like for all four current sources in parallel can be seen in Figure 43. All current
sources work synchronously to each other with a fixed and parallel start point.
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Figure 43. Single Pulse Mode - Example
8.10.2 Multiple Pulse Mode
In addition to the Single Pulse Pattern Mode described in Section 8.10.1 there is a second mode which is basically based on the Single Pulse
Mode. The Multiple Pulse Mode still uses the parameters tr_CURR, tf_CURR, ton_CURR and toff_CURR of the Single Pulse Mode but has two
more parameters. The first parameter is tp_CURR and can be configured in register tp_led. This register defines the pause time between two
pulses. The second new parameter is a parameter that defines the number of multiple pulses. This can be configured in register multiple_pulse
Table 33. Timing Multiple Pulse Mode
The new parameter can be found in Table 34. All other parameters keep the same and are shared with the Single Pulse Mode. These
parameters can be found in Table 32. /
Table 34. Singe Pulse Mode Parameters
Symbol
Parameter
tp_CURR
Pause time between
multiple pulses
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Condition
Min
0
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Max
Unit
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Please mind that the settings for tr_CURR, tf_CURR, ton_CURR, toff_CURR and tp_CURR and the pulse count number in register multiple_pulse
are valid for all four current sinks at the same time. It is not possible to define individual time values for each current source differently to each
other. The only parameter which can differ from on current source to another is the current which can be configured in registers curr1_current,
curr2_current, curr3_current and curr4_current for each current source independently.
Figure 44. Multiple Pulse Mode - Example
8.10.3 Frame Mask Mode
An additional feature for creating unique LED lighting effects is the Frame Mask Mode. In order to use this mode there is no additional timing
parameter necessary. All the timing parameters described in Section 8.10.1 and Section 8.10.2 are also valid for this third mode and can be
combined together. There are no restrictions when using this mode together with Single- or Multiple Pulse Mode. For a better understanding how
this special mode works a timing diagram example can be found in Figure 45 below.
Figure 45. Multiple Pulse Mode - Example
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As the example shows, each defined pattern, no matter if it is a single pulse or multiple pulse pattern, can be divided into frames which are
basically running in parallel mode. The pattern which has be defined with the different parameters like tr_CURR, ton_CURR, toff_CURR and
tp_CURR is repeated in an endless loop. In order to enhance the functionality of the pattern generation it is possible to mask or skip frames in
between the endless pattern loop. Each current source comes with a dedicated register to support masking of one frame up to four frames. This
means the Frame Mask Mode allows the user to individually skip frames in each current source. The example above shows that the Frame Mask
Register fmask_curr2 of CURR2 has been set to 1, which means every second frame will be masked out when playing the pattern. The Frame
Mask Register fmask_curr3 of CURR3 has been set to 2, therefore two frames are masked out in the example. The register fmask_curr4 of
CURR4 has been set to 3, thus three frames are masked out in the example. The frame mask order in the example is not fixed and can be easily
exchanged depending on the Frame Mask Register setting for each current source.
8.10.4 Frame Start Delay Mode
The frame delay mode allows the user to add a start-delay for each current source separately in pattern generation mode. This feature allows an
user to create again more complex lighting patterns like a running LED shown in the example in Figure 46.
Figure 46. Frame Start Delay Mode
Each current source has a dedicated delay register(frame_delay1, frame_delay2, frame_delay3 and frame_delay4) which allow adding different
start delays to each current source. This feature can of course be combined with the frame mask mode described in 8.10.3. In the example
above the frame_delay2 register has been set to 1 to add one frame delay to CURR2. The frame_delay3 register has been set to 2 adding two
frames startup delay to CURR3. CURR4 needs a startup delay of 3 frames which means theframe_delay4 registers must be set to 3. It is worth
mentioning that there are also no restrictions when using this mode together with Single- or Multiple Pulse mode described in chapter 8.10.1 and
8.10.2.
8.10.5 GPIO Toggle Mode
An add on feature which enables the user to use up to eight LEDs in pattern generation mode in a sequential order is the GPIO Toggle mode.
Figure 47. GPIO Toggle Mode 1 Frame
The mode can be enabled with the register gpio_toggle_en. Once the mode has been enabled register gpio_toggle_framenr gets activated and
allows the user to select after how many frames the GPIO/AUDIO_IN pin toggles. An example is shown in Figure 47 above. The gpio_toggle_en
register has been set to 1. The gpio_toggle_framenr register has also been set to 1. The GPIO/AUDIO_IN pin toggles after each frame. The pin
can be used to control an external switch to enable some more LEDs. An example of such an application is shown in Figure 48. Please mind that
it is not possible to operate all eight LEDs in parallel. It is only possible to enable either one or the other block. This mechanism is handled
automatically with the external control transistors.
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Figure 48. Application Proposal GPIO Toggle Mode
8.10.6 LED Pattern Control Registers
Table 35. PWM Control Register
0x15 PWM Control Register
Bit
Bit Name
1
pwm_dim_shape
Default
0
0
Access
R/W
R/W
Defines the PWM source. It can either be selected the internal PWM
generator to dim the current sources or us the pin GPIO/AUDIO_IN as PWM
input.
0: internal PWM generator
1: external PWM input selected (GPIO/AUDIO_IN)
pwm_src
0
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Bit Description
This bit defines if the current sources do logarithmic or linear up/down
dimming.
0: logarithmic dimming
1: linear dimming
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Table 36. PWM Control Register
0x16 PWM Timing Register
Bit
Bit Name
7:4
pwm_dim_speed_up
Default
0x08
3:0
Access
R/W
These bits define the value of tr_CURR which is the dim speed when
dimming up and down the current sources. The dim speed is valid for all
current sources at the same time.
0000: immediate
0001: 0.12s
0010: 0.25s
0011: 0.38s
0100: 0.51s
0101: 0.77s
0110: 1.0s
0111: 1.6s
1000: 2.1s
1001: 2.6s
1010: 3.1s
1011: 4.2s
1100: 5.2s
1101: 6.2s
1110: 7.3s
1111: 8.3s
R/W
These bits define the value of tr_CURR which is the dim speed when
dimming up and down the current sources. The dim speed is valid for all
current sources at the same time.
0000: immediate
0001: 0.12s
0010: 0.25s
0011: 0.38s
0100: 0.51s
0101: 0.77s
0110: 1.0s
0111: 1.6s
1000: 2.1s
1001: 2.6s
1010: 3.1s
1011: 4.2s
1100: 5.2s
1101: 6.2s
1110: 7.3s
1111: 8.3s
pwm_dim_speed_down
0x08
Bit Description
Table 37. PWM Trigger Register
0x17 PWM Trigger Register
Bit
Bit Name
4
start_dim
Default
0
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Access
R/W
Bit Description
This bit defines in PWM mode of the current sources if the outputs are
switched on/off directly or dimmed up/down using the timing of register
pwm_dim_speed_up.
0: direct on/off of current sources
1: logarithmic/linear - up/down dimming of current sources
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Table 37. PWM Trigger Register
0x17 PWM Trigger Register
Bit
Bit Name
3
dim_curr4
Default
Access
Bit Description
R
A register read of this register reflects the status of current source CURR4. If
the register returns 0, the current source is switched off. If the register
returns 1, the current source is switch on with the current defined in register
curr4_current.
0: Current Source CURR4 is switched off
1: Current Source CURR4 is switched on
W
A write to this register defines the target value for CURR4. If 0 is written to
this register CURR4 is switched off or dimmed down depending on register
start_dim. If 1 is written to this register CURR4 is switched on or dimmed up
depending on register start_dim. Mind that this setting is only effective if
CURR4 is configured to PWM mode in register curr4_mode.
0: Target value of CURR4 for dimming down or direct control
1: Target value of CURR4 for dimming up or direct control
R
A register read of this register reflects the status of current source CURR3. If
the register returns 0, the current source is switched off. If the register
returns 1, the current source is switch on with the current defined in register
curr3_current.
0: Current Source CURR3 is switched off
1: Current Source CURR3 is switched on
W
A write to this register defines the target value for CURR3. If 0 is written to
this register CURR3 is switched off or dimmed down depending on register
start_dim. If 1 is written to this register CURR3 is switched on or dimmed up
depending on register start_dim. Mind that this setting is only effective if
CURR3 is configured to PWM mode in register curr3_mode.
0: Target value of CURR3 for dimming down or direct control
1: Target value of CURR3 for dimming up or direct control
R
A register read of this register reflects the status of current source CURR2. If
the register returns 0, the current source is switched off. If the register
returns 1, the current source is switch on with the current defined in register
curr2_current.
0: Current Source CURR2 is switched off
1: Current Source CURR2 is switched on
W
A write to this register defines the target value for CURR2. If 0 is written to
this register CURR2 is switched off or dimmed down depending on register
start_dim. If 1 is written to this register CURR2 is switched on or dimmed up
depending on register start_dim. Mind that this setting is only effective if
CURR2 is configured to PWM mode in register curr2_mode.
0: Target value of CURR2 for dimming down or direct control
1: Target value of CURR2 for dimming up or direct control
R
A register read of this register reflects the status of current source CURR1. If
the register returns 0, the current source is switched off. If the register
returns 1, the current source is switch on with the current defined in register
curr1_current.
0: Current Source CURR1 is switched off
1: Current Source CURR1 is switched on
W
A write to this register defines the target value for CURR1. If 0 is written to
this register CURR1 is switched off or dimmed down depending on register
start_dim. If 1 is written to this register CURR1 is switched on or dimmed up
depending on register start_dim. Mind that this setting is only effective if
CURR1 is configured to PWM mode in register curr1_mode.
0: Target value of CURR1 for dimming down or direct control
1: Target value of CURR1 for dimming up or direct control
0
2
dim_curr3
0
1
dim_curr2
0
0
dim_curr1
0
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Table 38. Pattern Timing Register
0x18 Pattern Timing Register
Bit
Bit Name
5:3
pattern_toff
Default
0x03
2:0
Access
R/W
These bits define the value of the parameter toff_CURR. It defines the off
time of CURR1, CURR2, CURR3 and CURR4 in pattern generation mode.
The same value is used for all four current sources in parallel.
000: 0.08s
001: 0.15s
010: 0.28s
011: 0.54s
100: 1.1s
101: 2.1s
110: 4.2s
111: 8.4s
R/W
These bits define the value of the parameter ton_CURR. It defines the on
time of CURR1, CURR2, CURR3 and CURR4 in pattern generation mode.
The same value is used for all four current sources in parallel.
000: 0.04s
001: 0.07s
010: 0.14s
011: 0.27s
100: 0.53s
101: 1.1s
110: 2.1s
111: 4.2s
pattern_ton
0
Bit Description
Table 39. Pattern Multiple Pulse Register
0x19 Pattern Multiple Pulse Register
Bit
Bit Name
7:6
multiple_pulse
Default
0
1:0
Access
R/W
Defines the number of multiple pulses applied to all current sources at the
same time.
00: 1 pulse
01: 2 pulses
10: 3 pulses
11: 4 pulses
R/W
These bits define the value of parameter tp_CURR. It defines the pause time
for multiple pulse mode in pattern generation mode.
00: 0ms
01: 150ms
10: 280ms
11: 540ms
tp_led
0
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Bit Description
Revision 1.13
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AS3668
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 40. Pattern Frame Mask Register
0x1a Pattern Frame Mask Register
Bit
Bit Name
7:6
fmask_curr4
Default
0
5:4
R/W
Defines the frames to be masked out in pattern generation mode for current
source CURR4.
00: No frame mask for CURR4
01: Mask 1 frame for CURR4
10: Mask 2 frames for CURR4
11: Mask 3 frames for CURR4
R/W
Defines the frames to be masked out in pattern generation mode for current
source CURR3.
00: No frame mask for CURR3
01: Mask 1 frame for CURR3
10: Mask 2 frames for CURR3
11: Mask 3 frames for CURR3
R/W
Defines the frames to be masked out in pattern generation mode for current
source CURR2.
00: No frame mask for CURR2
01: Mask 1 frame for CURR2
10: Mask 2 frames for CURR2
11: Mask 3 frames for CURR2
R/W
Defines the frames to be masked out in pattern generation mode for current
source CURR2.
00: No frame mask for CURR1
01: Mask 1 frame for CURR1
10: Mask 2 frames for CURR1
11: Mask 3 frames for CURR1
fmask_curr2
0
1:0
Bit Description
fmask_curr3
0
3:2
Access
fmask_curr1
0
Table 41. Pattern Start Control Register
0x1b Pattern Start Control Register
Bit
Bit Name
2
pattern_phase_out
1
0
Default
Access
0
R/W
0
W
1
R/W
pattern_enable
pattern_start_src
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Bit Description
The bit defines the way how a pattern is being stopped when the
pattern_enable register is cleared. If the bit is set to 0 and the
pattern_enable register is cleared the running pattern stops immediately. If
the bit is set to 1 and the pattern_enable is cleared the pattern finishes the
running frame and stops afterwards.
0: Stop pattern immediately
1: Phase-out pattern
Starts the pattern generation on current sources.
0: Pattern generation off
1: Start of pattern generation
Selects the input source to trigger the pattern generation start.
0: Pattern enable by software bit
1: pattern enable by GPIO/AUDIO_IN
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AS3668
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 42. Pattern Frame Start Delay Register
0x1c Pattern Frame Start Delay Register
Bit
Bit Name
7:6
frame_delay4
Default
0
5:4
1:0
R/W
R/W
Defines the start delay of CURR3 in pattern generation mode. Note that
changes in this register are only getting active after a restart of the pattern
generation unit by toggling the pattern_enable bit.
00: No start delay for CURR3
01: 1 frame start delay for CURR3
10: 2 frames start delay for CURR3
11: 3 frames start delay for CURR3
R/W
Defines the start delay of CURR2 in pattern generation mode. Note that
changes in this register are only getting active after a restart of the pattern
generation unit by toggling the pattern_enable bit.
00: No start delay for CURR2
01: 1 frame start delay for CURR2
10: 2 frames start delay for CURR2
11: 3 frames start delay for CURR2
R/W
Defines the start delay of CURR1 in pattern generation mode. Note that
changes in this register are only getting active after a restart of the pattern
generation unit by toggling the pattern_enable bit.
00: No start delay for CURR1
01: 1 frame start delay for CURR1
10: 2 frames start delay for CURR1
11: 3 frames start delay for CURR1
frame_delay2
0
frame_delay1
0
Bit Description
Defines the start delay of CURR4 in pattern generation mode. Note that
changes in this register are only getting active after a restart of the pattern
generation unit by toggling the pattern_enable bit.
00: No start delay for CURR4
01: 1 frame start delay for CURR4
10: 2 frames start delay for CURR4
11: 3 frames start delay for CURR4
frame_delay3
0
3:2
Access
Table 43. GPIO Toggle Control Register
0x1d GPIO Toggle Control Register
Bit
Bit Name
2
gpio_toggle_en
Default
0
1:0
Access
Bit Description
W
This bit enables the GPIO/AUDIO_IN pin to toggle after a defined number of
frames. The number of frames where the pin toggles is defined in register
gpio_toggle_framenr.
0: GPIO toggle disabled
1: GPIO toggle enabled
R/W
This register defines the number of frames where the GPIO/AUDIO_IN
toggles. The register setting is only active if gpio_toggle_en bit is enabled.
00: GPIO toggles after 1 frame
01: GPIO toggles after 2 frames
10: GPIO toggles after 3 frames
11: GPIO toggles after 4 frames
gpio_toggle_framenr
0
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AS3668 2V0
Data Sheet - R e g i s t e r M a p
9 Register Map
Table 44. I2C Register Overview
Addr
Name
b7
b6
b5
b4
b3
b2
b1
b0
Chip ID
3Eh
CHIP ID1
3Fh
CHIP ID2
chip_id1<7:0>
Constant value ‘b10100101’
chip_id2<7:4>
revision<3:0>
LED Control
01h
CurrX control
02h
CURR1 current
03h
04h
05h
2Bh
curr4_mode<7:6>
0: current source 4 off; 1:current source 4 on;
2: current source 4 PWM; 3: Current source 4 Patt.
curr3_mode<5:4>
0: current source 3 off; 1:current source 3 on;
2: current source 3 PWM; 3: Current source 3 Patt.
curr2_mode<3:2>
0: current source 2 off; 1:current source 2 on;
2: current source 2 PWM; 3: Current source 2 Patt.
curr1_mode<1:0>
0: current source 1 off; 1:current source 1 on;
2: current source 1 PWM; 3: Current source 1 Patt.
curr1_current<7:0>
Output current for current source CURR1 = 0mA ... 25.5mA; 256 steps of 0.1mA.
curr2_current<7:0>
CURR2 current
Output current for current source CURR2 = 0mA ... 25.5mA; 256 steps of 0.1mA.
curr3_current<7:0>
CURR3 current
Output current for current source CURR3 = 0mA ... 25.5mA; 256 steps of 0.1mA.
curr4_current<7:0>
CURR4 current
Output current for current source CURR4 = 0mA ... 25.5mA; 256 steps of 0.1mA.
CurrX low
voltage status
curr4_low_v
curr3_low_v
curr2_low_v
curr1_low_v
0: CURR4 voltage ok
1: CURR4 low voltage
0: CURR3 voltage ok
1: CURR3 low voltage
0: CURR2 voltage ok
1: CURR2 low voltage
0: CURR1 voltage ok
1: CURR1 low voltage
gpio_in_invert
gpio_in_en
gpio_mode
GPIO Control
06h
GPIO Control
07h
GPIO Output
08h
GPIO Signal
0: non-inverted dig. input 0: analog input
1: inverted digital input
1: digital input
0: Input only
1: Output (open drain)
gpio_out
0: GPIO pin low
1: GPIO pin high
gpio_in
0: GPIO pin low
1: GPIO pin high
PWM control
15h
PWM Control
16h
PWM Timing
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pwm_dim_shape
pwm_src
0: logarithmic ramp
1: linear ramp
0: internal PWM
1: external PWM
pwm_dim_speed_up<7:4>
pwm_dim_speed_down
0: immediate 1: 0.12s 2: 0.25s 3: 0.38s 4: 0.51s 5: 0.77s 6: 1.0s 7: 1.6s 8: 2.1s
9: 2.6s 10: 3.1s 11: 4.2s 12: 5.2s 13: 6.2s 14: 7.3s 15: 8.3s
0: immediate 1: 0.12s 2: 0.25s 3: 0.38s 4: 0.51s 5: 0.77s 6: 1.0s 7: 1.6s 8: 2.1s
9: 2.6s 10: 3.1s 11: 4.2s 12: 5.2s 13: 6.2s 14: 7.3s 15: 8.3s
Revision 1.13
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AS3668 2V0
Data Sheet - R e g i s t e r M a p
Table 44. I2C Register Overview
Addr
17h
Name
b7
b6
b5
PWM Trigger
b4
start_dim
b3
dim_curr4
b2
dim_curr3
b1
dim_curr2
b0
dim_curr1
0: no dimming
1: start log dimming
0: CURR4 off
1: CURR4 on
0: CURR3 off
1: CURR3 on
0: CURR2 off
1: CURR2 on
0: CURR1 off
1: CURR1 on
Pattern Control
18h
Pattern Timing
19h
Multiple Pulse
pattern_toff<5:3>
pattern_ton<2:0>
000: 0.08s 001: 0.15s 010: 0.28s 011: 0.54s
100: 1.1s 101: 2.1s 110: 4.2s 111: 8.4s
000: 0.04s 001: 0.07s 010: 0.14s 011: 0.27s
100: 0.53s 101: 1.1s 110: 2.1s 111: 4.2s
multiple_pulse<7:6>
tp_led<1:0>
00: 1 pulse 01: 2 pulses
10: 3 pulses 11: 4 pulses
00: 0ms 01: 150ms
10: 280ms 11: 540ms
fmask_curr4<7:6>
fmask_curr3<5:4>
fmask_curr2<3:2>
fmask_curr1<1:0>
00: No frame mask for CURR4
01: Mask 1 frame for CURR4
10: Mask 2 frame for CURR4
11: Mask 3 frame for CURR4
00: No frame mask for CURR3
01: Mask 1 frame for CURR3
10: Mask 2 frame for CURR3
11: Mask 3 frame for CURR3
00: No frame mask for CURR2
01: Mask 1 frame for CURR2
10: Mask 2 frame for CURR2
11: Mask 3 frame for CURR2
00: No frame mask for CURR1
01: Mask 1 frame for CURR1
10: Mask 2 frame for CURR1
11: Mask 3 frame for CURR1
1Ah
Frame Mask
1Bh
Start Control
1Ch
Pattern Frame frame_delay4
0: no delay 1: CURR4 1 frame delay
Start Delay
2: CURR4 2 frames delay 3:CURR4 3 frames delay
1Dh
GPIO toggle
control
pattern_phase_out pattern_enable
0: turn off immediately
1: phase out pattern
0: pattern off
1: start pattern
pattern_start_src
0: Softw. pattern enable
1: GPIO pattern enable
frame_delay3
frame_delay2
frame_delay1
0: no delay 1: CURR3 1 frame delay
2: CURR3 2 frames delay 3:CURR3 3 frames delay
0: no delay 1: CURR2 1 frame delay
2: CURR2 2 frames delay 3:CURR2 3 frames delay
0: no delay 1: CURR1 1 frame delay
2: CURR1 2 frames delay 3:CURR1 3 frames delay
gpio_toggle_en
gpio_toggle_framenr
0: disabled
1: enabled
0: 1 frame 1: 2 frames
2: 3 frames 3: 4 frames
adc_select
adc_mode
adc_on
0: Audip Preamplifier
1: GPIO direct
0: linear ADC
1: logarithmic ADC
0: ADC off
1: ADC on
ADC Result
26h
27h
ADC Result
Charge Pump
00h
adc_result<3:0>
cp_on
Reg Control
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0: Charge Pump off
1: Charge Pump on
Revision 1.13
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AS3668 2V0
Data Sheet - R e g i s t e r M a p
Table 44. I2C Register Overview
Addr
23h
Name
b7
CP Control
b6
cp_auto_on
b5
b4
cp_start_debounce cp_mode_switching
0: Manual CP Mode
1: automatic CP Mode
0: 32ms debounce time
1: 240μs debounce time
b3
b2
cp_mode
b1
0: 1:1 mode
1: 1:2 mode
0: Automatic Mode
1: Manual Mode
b0
cp_clk
0: 1MHz
1: 500kHz
Overtemperature Control
29h
Overtemp
Control
vmon_vbat<6:5>
shutdown_enable
0: ~2V - Shutdown Mode 01: 3.0V - Standby Mode
10: 3.15V - Standby Mode 11: 3.3V - Standby Mode
0: disable shutdown
1: enable shutdown
rst_ov_temp
decay_agc_down<4:3>
decay_agc_up<2:1>
agc_on
00: 0.131s 01: 0.262s
10: 0.393s 11: 0.524s
00: 0.262s 01: 0.524s
10: 0.786s 11: 1.049s
0: AGC switched off
1: AGC switched on
ov_temp
ov_temp_on
0: temp supervision off
1: temp supervision on
Audio Control
40h
Audio AGC
41h
Audio Input
Buffer
agc_up_level
agc_down_level
0: Normal AGC up
switching level threshold
1: AGC up switching
threshold increased
0: Normal AGC down
switching level threshold
1: AGC down switching
threshold increased
audio_gain<5:1>
Controls the audio input gain from -6dB ... +25dB in 1dB steps
audio_dis_start
audio_man_start
0: input cap precharge
1: no precharging
0: auto precharge
1: manual precharge
audio_input_pin
pld_off
0: GPIO
1: CURR4
0: Pull down enabled
1: Pull down disabled
adc_characteristic
42h
Audio Control
0: x*250mV (linear)
1: x*50mV (linear)
x
0: 75mV*2 (log)
x
000: 4 LED bar code 001: 4 LED bar code with dimming
010: running LED bar code 011: running LED bar code with dimming 100: RGB
101: RGB with dimming 110: 4 LED parallel with dimming 111: -
00: 10ms 01: 20ms
10: 40ms 11: 80ms
Audio Output
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0: Audio Buffer off
1: Audio Buffer on
audiosync_mode<2:0>
audio_decay<4:3>
1: 75mV*2 (log)
43h
aud_buf_on
curr4_aud_en
curr3_aud_en
curr2_aud_en
0: CURR4 normal mode
1: CURR4 audio sync
0: CURR3 normal mode
1: CURR3 audio sync
0: CURR2 normal mode
1: CURR2 audio sync
curr1_aud_en
0: CURR1 normal
mode
1: CURR1 audio sync
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AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
10 Application Information
10.1 LED Software Implementation Examples
10.1.1 Simple Breathlight Pattern with one LED
In this example we’d like to use CURR1 in pattern generation mode to create a simple breathlight pattern without continuous I2C traffic. This
helps to unload the calculation power from the CPU.
Figure 49. Simple Breathlight Pattern Example
The timing example shown in Figure 49 above, can be easily implemented with just a couple of I2C commands.
Table 45. Code Example Simple Breathlight Pattern
Register Name
Address
Write Value
CurrX Control
0x01
0x03
CURR1 Current
0x02
0x96
Comments
Enable CURR1 for pattern generation mode. Other
current sources are off
Set the output current of CURR1 to 15mA.
PWM Timing
0x16
0x55
Define Rise/Fall time with 0,77s
Pattern Timing
0x18
0x32
Define 0,15s on time and 4,21s off time
Start Control
0x1B
0x02
Start breathlight pattern
10.1.2 Dual Pulse Pattern with one LED
In this example we would like to use CURR1 in pattern generation mode to create a simple dual pulse pattern without continuous I2C traffic. This
helps again to unload the CPU.
Figure 50. Dual Pulse Pattern Example
The timing example shown in Figure 50 above, can be easily implemented with just a couple of I2C commands.
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AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Table 46. Code Example Dual Pulse Pattern Example
Register Name
Address
Write Value
CurrX Control
0x01
0x03
CURR1 Current
0x02
0xFF
Comments
Enable CURR1 for pattern generation mode. Other
current sources are off
Set the output current of CURR1 to 25,5mA.
PWM Timing
0x16
0x11
Define Rise/Fall time with 0,12s
Pattern Timing
0x18
0x30
Define 0,04s on time and 4,2s off time
Multiple Pulse
0x19
0x41
Define 2 pulses and 150ms pause time
Start Control
0x1B
0x02
Start breathlight pattern
10.1.3 RGB LED Pattern
In this example we would like to demonstrate how to use an RGB LED which is connected to CURR1, CURR2 and CURR3.
Figure 51. RGB Pulse Pattern Example
With the timing example above you get a mixture of red, green and blue color. Table 43 below shows how to configure the device to get the
pattern shown in Figure 51.
Table 47. Code Example RGB Pulse Pattern
Register Name
Address
Write Value
CurrX Control
0x01
0x3F
CURR1 Current
0x02
0x4F
Comments
Enable CURR1, CURR2 and CURR3 for pattern
generation mode. CURR4 is in off mode.
Set the output current of CURR1 to 7,9mA.
CURR2 Current
0x03
0xC8
Set the output current of CURR2 to 20mA.
CURR3 Current
0x04
0xB6
Set the output current of CURR3 to 18,2mA.
PWM Timing
0x16
0x88
Define Rise/Fall time with 2.1s
Pattern Timing
0x18
0x25
Define 1,1s on time and 1,1s off time
Multiple Pulse
0x19
0x00
Define single pulse mode
Start Control
0x1B
0x02
Start breathlight pattern
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AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
10.1.4 Parallel Up - Dimming
In this example we would like to demonstrate how to do simple PWM up-dimming of all four LEDs in parrallel.
Figure 52. PWM Up-Dimming Example
If the output current of all four current sources is configured according to the requirements of the application it is possible to dimm the LEDs up
with a single I2C command.
Table 48. Code Example Up-Dimming
Write Value
CurrX Control
Address
0x01
0xAA
Comments
Enable CURR1, CURR2, CURR3 and CURR4 for PWM mode.
CURR1 Current
0x02
0x64
Set the output current of CURR1 to 10mA.
CURR2 Current
0x03
0x64
Set the output current of CURR2 to 10mA.
CURR3 Current
0x04
0x64
Set the output current of CURR3 to 10mA.
CURR4 Current
0x05
0x64
Set the output current of CURR4 to 10mA.
PWM Timing
0x16
0x77
PWM Trigger
0x17
0x1F
Define dimming time with 1.6s
Start up-dimming of all current sources with 1.7s
dimming time.
Register Name
10.1.5 Parallel Down- Dimming
In this example we would like to demonstrate how to do simple PWM down-dimming of all four LEDs in parallel.
Figure 53. PWM Down-Dimming Example
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Revision 1.13
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AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Table 49. Code Example Down-Dimming
Write Value
CurrX Control
Address
0x01
0xAA
Comments
Enable CURR1, CURR2, CURR3 and CURR4 for On mode.
CURR1 Current
0x02
0x64
Set the output current of CURR1 to 10mA.
CURR2 Current
0x03
0x64
Set the output current of CURR2 to 10mA.
CURR3 Current
0x04
0x64
Set the output current of CURR3 to 10mA.
CURR4 Current
0x05
0x64
PWM Trigger
0x17
0x0F
PWM Timing
0x16
0x77
PWM Trigger
0x17
0x10
Set the output current of CURR4 to 10mA.
Enable CURR1, CURR2, CURR3 and CURR4 for PWM mode.
All four current sources keep switched on when we
change from On Mode to PWM Mode.
Define dimming time with 1.6s
Start down-dimming of all current sources with 1.7s
dimming time.
Register Name
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Revision 1.13
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Revision 1.13
D
C
B
A
C2
1
CPU for I2C control
GND
DIGITAL_IO
10k
R1
DIGITAL_IO
10k
R2
2
2
GND
C4
1uF
VBAT
D3
B3
C3
C2
GPIO
SCL
SDA
VBAT
U1
AS3668
A2
C1
A3
Controller
GND
3
Curr4
Curr3
Breathlight-
Curr1
Curr2
4-channel
3
VCP
470nF
AS3668
CP
D2
GND
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CN
1
CURR2
CURR3
CURR4
A1
D1
CURR1
C1
B2
B1
GND
GND
1uF
C3
D1
GND
D2
GND
D3
GND
4
4
D4
D
C
B
A
AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
10.2 Hardware Examples
Figure 54. AS3668 Standard 4 Channel LED Application Example
51 - 59
Revision 1.13
D
C
B
A
C2
1
CPU for I2C control
GND
DIGITAL_IO
10k
R2
2
10k
R3
DIGITAL_IO
Battery Terminal
Device to be controlled
with AS3668
10k
R1
DIGITAL_IO
GND
C4
1uF
VBAT
D3
B3
C3
C2
GPIO
SCL
SDA
VBAT
U1
AS3668
A2
C1
A3
3
Curr2
Curr3
BreathlightController
GND
3
Curr4
Curr1
4-channel
VCP
470nF
AS3668
CP
2
GND
D2
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CN
1
CURR2
CURR3
C1
A1
D1
CURR1
B2
B1
GND
1uF
C3
GND
D2
GND
D3
GND
4
4
D4
D
C
B
A
AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 55. AS3668 Standard RGB LED Operation with GPIO Control Application Example
52 - 59
Revision 1.13
D
C
B
A
C2
1
Audio DAC or Amplifier
CPU for I2C control
GND
DIGITAL_IO
Left Channel
Right Channel
10k
R1
DIGITAL_IO
R4
R3
10k
R2
1k
1k
2
C5
470nF
Battery Terminal
D3
B3
C3
C2
GPIO
SCL
SDA
VBAT
U1
AS3668
C1
A3
Curr2
Curr3
BreathlightController
GND
Curr4
Curr1
4-channel
AS3668
VCP
470nF
3
CURR1
CURR2
CURR3
CURR4
B2
C1
A1
D1
B1
3
CURR4 can also be configured as Audio Input
GND
C4
1uF
VBAT
A2
CP
2
GND
D2
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CN
1
GND
GND
1uF
C3
D1
GND
D2
GND
D3
GND
4
4
D4
D
C
B
A
AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 56. AS3668 Audio Synchronization Application Example
53 - 59
Revision 1.13
D
C
B
A
C2
1
Integrated Charger
Circuit
CPU for I2C control
GND
DIGITAL_IO
10k
R5
Q1
10k
R2
Battery Terminal
GND
C4
1uF
VBAT
2
The LED driver output of a charger can be linked together
with the GPIO input of AS3668 to indicate trickle charging
with a default breathlight pattern on CURR1 while the CPU
is not working at all.
VBAT
10k
R1
DIGITAL_IO
D3
B3
C3
C2
GPIO
SCL
SDA
VBAT
U1
AS3668
A2
C1
A3
3
Curr2
Curr3
BreathlightController
GND
3
Curr4
Curr1
4-channel
VCP
470nF
AS3668
CP
2
GND
D2
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1
CURR3
A1
GND
470nF
C5
CURR2
C1
D1
CURR1
B2
B1
1uF
C3
1k
R3
1k
R4
GND
Right Channel
Left Channel
GND
D2
GND
D4
4
Audio DAC or Amplifier
D3
4
D
C
B
A
AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 57. AS3668 Charger Application Example with Audio Synchronization
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Revision 1.13
D
C
B
C2
1
Audio DAC or Amplifier
CPU for I2C control
GND
DIGITAL_IO
Left Channel
Right Channel
10k
R1
DIGITAL_IO
R4
R3
10k
R2
1k
1k
C5
470nF
Battery Terminal
2
GND
C4
1uF
VBAT
D3
B3
C3
C2
GPIO
SCL
SDA
VBAT
U1
AS3668
C1
Curr2
Curr3
4-channel
BreathlightController
GND
Curr4
Curr1
VCP
470nF
AS3668
D2
A
2
A2
CP
A3
CN
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GND
1
CURR2
CURR3
CURR4
C1
A1
D1
3
CURR1
B2
B1
3
GND
1uF
C3
GND
Q1
D3
D4
10k
R5
D5
GND
Q2
D6
4
Please mind that the RGB LEDs can't be used at the same
time with the white LEDs.
D2
4
D7
D
C
B
A
AS3668
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 58. AS3668 Dual RGB LED Application Example
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AS3668
Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
11 Package Drawings and Markings
The device is available in a 12-pin WL-CSP (1.255x1.680mm) package.
Figure 59. 12-pin WL-CSP (1.255x1.680mm) Marking
Table 50. Packaging Code XXXX
XXXX
encoded Datecode
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Revision 1.13
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AS3668
Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
www.ams.com/AS3668
Revision 1.13
ccc Coplanarity
All dimensions in μm
Notes:
Figure 60. 12-pin WL-CSP (1.255x1.680mm) Package Drawing
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AS3668
Data Sheet - O r d e r i n g I n f o r m a t i o n
12 Ordering Information
The devices are available as the standard products shown in Table 51.
Table 51. Ordering Information
Ordering Code
Marking
Description
Delivery Form
Package
AS3668-BWLT
AS3668
4-channel smart LED driver
Tape & Reel
12-pin WL-CSP (1.255x1.680mm)
Note: All products are RoHS compliant and ams green.
Buy our products or get free samples online at www.ams.com/ICdirect
Technical Support is available at www.ams.com/Technical-Support
For further information and requests, email us at [email protected]
(or) find your local distributor at www.ams.com/distributor
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Revision 1.13
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AS3668
Data Sheet - C o p y r i g h t s
Copyrights
Copyright © 1997-2013, ams AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights
reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the
copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams AG makes no
warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described
devices from patent infringement. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior
to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in normal
commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability
applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing
by ams AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard
production flow, such as test flow or test location.
The information furnished here by ams AG is believed to be correct and accurate. However, ams AG shall not be liable to recipient or any third
party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or
indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the
technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other
services.
Contact Information
Headquarters
ams AG
Tobelbaderstrasse 30
A-8141 Unterpremstaetten, Austria
Tel
Fax
: +43 (0) 3136 500 0
: +43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
http://www.ams.com/contact
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