AS1344

AS1344
Datasheet
AS1344
4 2 V, D C - D C B o o s t C o n v e r t e r w it h a d j u s ta b l e S o fts ta r t
1 General Description
2 Key Features
The AS1344 boost converter contains a 1.4A internal
switch in a tiny TDFN-10 3x3mm package. The device
operates from a 0.9V to 3.6V supply, and can boost voltages up to 42V output.
The output voltage can easily be adjusted by an external
resistor divider.
The AS1344 uses a unique control scheme providing
the highest efficiency over a wide range of load conditions. An internal 1.4A MOSFET reduces external component count, and a fixed high switching frequency
(1MHz) allows for tiny surface-mount components.
The AS1344 also features power-OK circuitry which
monitors the output voltage.
The device also offers a Softstart function which limits
the current during startup. The current during startup
can be easily adjusted with the value of RV. For RV =
0Ω, there is no softstart.
Additionally the AS1344 features a low quiescent supply
current and a shutdown mode to save power. During
shutdown an output disconnect switch separates the
input from the output.
The AS1344 is ideal for LCD or OLED panels with low
current requirements and can also be used in a wide
range of other applications.
The device is available in a low-profile TDFN-10 3x3mm
package.
!
5.5V to 42V Adjustable Output Voltage
!
0.9V to 3.6V Supply Voltage Range
!
High Output Current:
- 30mA @ 12V VOUT, from 1.5V VCC
!
Efficiency: Up to 85%
!
Switching Frequency: 1MHz
!
Output Disconnect Function
!
Softstart Function with adjustable Current Limit
!
Output Discharge Function
!
Power-OK Output
!
Quiescent Current: 22µA
!
Shutdown Current: 0.1µA
!
TDFN-10 3x3mm Package
3 Applications
The device is ideal for OLED display power supply, LCD
bias generators, mobile/cordless phones, palmtop computers, PDAs and organizers, handy terminals, driving
LEDs or any other portable, battery-powered device.
Figure 1. AS1344 - Typical Application Diagram
L1
RV
VCC = 0.9V
to 3.6V
VIN
CIN
VOUT
R3
D1
POK
On
Off
SWOUT
VCC
AS1344
LX
R1
VOUT = 5.5V to 42V
COUT
VCC
GND
FB
EN
R2
GND
PGND
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AS1344
Datasheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
EN 1
10 FB
POK 2
GND 3
9 VOUT
AS1344
VCC 4
8 VIN
7 SWOUT
PGND 5
6 LX
Pin Descriptions
Table 1. Pin Descriptions
Pin Number
Pin Name
1
EN
2
POK
3
4
5
GND
VCC
PGND
6
LX
7
SWOUT
8
VIN
9
VOUT
10
FB
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Description
Active-High Enable Input. A logic low on this pin shuts down the device and
reduces the supply current to 0.1µA.
GND: device in shutdown.
VCC : normal operation.
Power-OK.
0: VOUT < 90% of VOUTNOM.
1: VOUT > 90% of VOUTNOM.
Ground
+0.9V to +3.6V Supply Voltage. Bypass this pin to GND with a ≥10µF capacitor.
Ground. Should be the starpoint of CIN and COUT.
Inductor. The drain of the internal N-channel MOSFET.
Note: This pin is high impedance in shutdown.
Shutdown Disconnect Switch Out. Disconnects the input from the output during
shutdown.
Supply Connection. Connect a resistor between pin VIN and pin VCC for limiting
the input current during startup.
+5.5 to +42V Output Voltage. This pin also powers the AS1344 after startup.
Bypass this pin to GND with a ≥4.7µF capacitor.
Feedback Pin. Feedback input to the gm error amplifier. Connect a resistor divider
tap to this pin. The output voltage can be adjusted from 5.5V to 42V by:
VOUT = 1.25V[1 + (R1/R2)]
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AS1344
Datasheet - 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 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Table 2. Absolute Maximum Ratings
Parameter
Min
Max
VCC, VIN, EN, SWOUT, POK, FB to GND
5
VOUT, LX to GND
45
Units
Comments
V
Thermal Resistance ΘJA
36.7
ºC/W
on PCB
ESD
2
kV
HBM MIL-Std. 883E 3015.7 methods
@25°C, JEDEC 78
Latch-Up
-200
+100
mA
Operating Temperature Range
-40
+85
ºC
Storage Temperature Range
-65
+150
ºC
125
ºC
Junction Temperature
Package Body Temperature
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+260
ºC
Revision 1.05
The reflow peak soldering temperature (body
temperature) specified is in accordance with
IPC/JEDEC J-STD-020D “Moisture/Reflow
Sensitivity Classification for Non-Hermetic
Solid State Surface Mount Devices”.
The lead finish for Pb-free leaded packages is
matte tin (100% Sn).
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AS1344
Datasheet - 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
VCC = EN = 3.6V, TAMB = -40 to +85ºC (unless otherwise specified). Typ values are at TAMB = +25ºC.
Table 3. Electrical Characteristics
Symbol
VCC
Parameter
Condition
Min
Typ
Maximum Supply Voltage
Max
Unit
3.6
V
Minimum Supply Voltage
VOUT = 12V, RV = 0Ω, no load
0.9
1.1
V
Minimum Start-Up Voltage
VOUT = 12V, ILOAD = 1mA, RV = 0Ω
0.95
1.2
V
42
V
VOUT
Output Voltage Range
5.5
IQ
Quiescent Current
VOUT = 6V, VFB=1.3V
22
30
µA
ISHDN
Shutdown Current
EN = GND, TAMB = +25ºC
0.02
1
µA
ΔVLNR
VCC Line Regulation
VOUT = 15V, ILOAD = 1mA,
VCC = 1.8 to 3.6V
0.05
%/V
ΔVLDR
Load Regulation
VOUT = 15V,
ILOAD = 0 to 20mA
0.01
%/mA
η
Efficiency
L1 = 6.8µH, VOUT = 12V, ILOAD = 50mA
85
%
VFB
Feedback Voltage
IFB
Feedback Input Bias Current
1.225
1.25
1.275
V
VFB = 1.3V
1
100
nA
DC-DC Switches
RLX
NMOS Switch OnResistance
ILX = 100mA
0.9
1.5
RP_ON
PMOS Switch OnResistance
ISWout = -100mA
0.3
1.0
ILX_LEAK
LX Leakage Current
VLX = 42V
15
IP_LEAK
Switch Leakage Current
P-channel
10
Ω
nA
Control Inputs
VIH
EN Input Threshold
1.1V ≤ VCC ≤ 3.6V
0.7 x
VCC
0.3 x
VCC
VIL
0
3.6
V
VEN
EN Input Voltage
V
IEN
EN Input Current
VEN = 0 to 3.6V
1
POK Output Low Voltage
POK sinking 1mA
0.01
0.2
V
POK Output High Leakage
Current
POK = 3.6V
1
500
nA
POK Threshold
Falling edge, referenced to VOUT(NOM)
87
90
93
%
Oscillator Frequency
0.85
1
1.15
MHz
Maximum Duty Cycle
90
95
nA
POK Output
VOL
Oscillator
fCLK
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AS1344
Datasheet - 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
Parts used for measurments: 6.8µH (MOS6020-682) Inductor, 10µF (GRM21BR60J106KE19) CIN and 4.7µF
(GRM32ER71H475KA88) COUT, (PMEG4010BEA) D1;
Figure 4. Efficiency vs. Output Current; VOUT = 12V
100
100
90
90
80
80
Efficiency (%)
Efficiency (%)
Figure 3. Efficiency vs. Output Current; VOUT = 6V
70
60
50
70
60
50
Vin = 2.0V
Vin = 2.0V
Vin = 2.5V
40
Vin = 2.5V
40
Vin = 3.0V
Vin = 3.0V
Vin = 3.3V
Vin = 3.3V
30
30
0.1
1
10
100
0.1
Output Current (mA)
10
100
Figure 6. Efficiency vs. Output Current; VOUT = 24V
100
80
90
70
60
80
Efficiency (%)
Efficiency (%)
Figure 5. Efficiency vs. Output Current; VOUT = 18V
70
60
50
Vin = 3.0V
40
50
40
30
20
Vin = 2.5V
Vin = 2.5V
Vin = 3.0V
10
Vin = 3.3V
30
Vin = 3.3V
0
0.1
1
10
0.1
100
Output Current (mA)
1
10
100
Output Current (mA)
Figure 7. Efficiency vs. Input Voltage; VOUT = 12V
Figure 8. Efficiency vs. Input Voltage; IOUT = 10mA
100
100
90
90
80
80
Efficiency (%)
Efficiency (%)
1
Output Current (mA)
70
60
50
70
60
50
Vout = 5.5V
Iout = 10mA
40
Vout = 10V
40
Iout = 50mA
Vout = 12V
Iout = 100mA
Vout = 15V
30
30
0.9 1.2 1.5 1.8 2.1
2.4 2.7
3
3.3 3.6
0.9 1.2 1.5 1.8 2.1
Input Voltage (V)
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2.4 2.7
3
3.3 3.6
Input Voltage (V)
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AS1344
Datasheet - 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 9. Output Voltage vs. Temperature;
VOUT=18V
Figure 10. Output voltage vs. Input Voltage;
VOUT=12V, (line regulation)
18.2
13
no l oad
Iout = 1mA
Iout = 10mA
Iout = 10mA
Iout = 20mA
Iout = 50mA
Iout = 100mA
18.1
Output Voltage (V)
Output Voltage (V)
Iout = 50mA
18
17.9
17.8
-45 -30 -15
12.5
12
11.5
11
0
15
30
45
60
75
90
0.9 1.2 1.5 1.8 2.1 2.4 2.7
Temperature (°C)
3
3.3 3.6
Input Voltage (V)
Figure 11. Output Voltage vs. Load Current;
VOUT=12V, VIN=1.5V, (load regualtion)
Figure 12. Maximum Output current vs. Input Voltage;
VOUT = 12, 15, 18, 24, 36V; (90% Voutnom)
12.5
300
Vout = 12V
12.4
Vout = 15V
Vout = 18V
Output Current (mA)
Output Voltage (V) .
12.3
12.2
12.1
12
11.9
11.8
Vout = 24V
Vout = 36V
200
100
11.7
11.6
0
11.5
0
10
20
0.9 1.2 1.5 1.8 2.1
30
Output Current (mA)
2.4 2.7
3
3.3 3.6
Input Voltage (V)
Figure 13. Maximum Output current vs. VOUT;
VCC = 1.5V, 3V
Figure 14. Start-Up Voltage vs. Output Current;
VCC = 0.9V to 3.6V, (95% Voutnom)
400
3.6
Vi n = 1.5V
3.3
Vi n = 3V
Start-Up Voltage (V)
Output Current (mA)
3
300
200
100
2.7
2.4
2.1
1.8
1.5
1.2
0.9
0.6
0
Vout = 5.5V
Vout = 12V
Vout = 15V
Vout = 18V
Vout = 24V
Vout = 36V
0.3
5
15
25
35
45
Output Voltage (V)
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0
10 20
30 40
50
60 70
80 90 100
Output Current (mA)
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AS1344
Datasheet - 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 15. Shutdown Current vs. Input Voltage
Figure 16. Shutdown Current vs. Temperature
3
Shutdown Current (µA) .
Shutdown Current (µA) .
0.025
0.02
0.015
0.01
0.005
0
0.9 1.2 1.5 1.8 2.1 2.4 2.7
3
2.5
2
1.5
1
0.5
0
-45 -30 -15
3.3 3.6
Input Voltage (V)
Figure 17. Switching Frequency vs. Temperature
15
30
45
60
75
90
75
90
Figure 18. Feedback Voltage vs. Temperature
1.1
1.3
Feedback Voltage (V) .
Switching Frequency (MHz) .
0
Temperature (°C)
1.05
1
0.95
0.9
-45 -30 -15
0
15
30
45
60
75
90
1.275
1.25
1.225
1.2
-45 -30 -15
Temperature (°C)
0
15
30
45
60
Temperature (C°)
Figure 19. Quiescent Current vs. Input Voltage
Quiescent Current (µA) .
22
21.5
21
20.5
20
0.9 1.2 1.5 1.8 2.1 2.4 2.7
3
3.3 3.6
Input Voltage (V)
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AS1344
Datasheet - 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
2V/Div
10V/DIV
2.5ms/Div
200mA/Div
EN
10V/DIV
IIN
VOUT
200mA/Div
10V/DIV
2V/Div
Figure 25. Startup Waveform, detail; VIN = 3.0V,
COUT = 170µF, RV = 3Ω
2V/Div
Figure 24. Startup Waveform; VIN = 3.0V,
COUT = 170µF, RV = 3Ω
EN
200mA/Div
EN
IIN
VOUT
VOUT
10V/DIV
IIN
200mA/Div
EN
2V/Div
Figure 23. Startup Waveform, detail; VIN = 2.4V,
COUT = 170µF, RV = 3Ω
100ms/Div
IIN
200mA/Div
EN
IIN
2.5ms/Div
Figure 22. Startup Waveform; VIN = 2.4V,
COUT = 170µF, RV = 3Ω
VOUT
10V/DIV
10V/DIV
VOUT
200mA/Div
EN
IIN
VOUT
100ms/Div
100ms/Div
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2V/Div
Figure 21. Startup Waveform, detail; VIN = 1.8V,
COUT = 170µF, RV = 3Ω
2V/Div
Figure 20. Startup Waveform; VIN = 1.8V,
COUT = 170µF, RV = 3Ω
2.5ms/Div
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AS1344
Datasheet - 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
200mV/DIV
VIN
VOUT(AC)
200mV/DIV
VIN
VOUT(AC)
2.5V 3.0V
Figure 27. Transient Line Regulation;
VOUT = 18V, ILOAD = 20mA
2.5V 3.0V
Figure 26. Transient Line Regulation;
VOUT = 18V, ILOAD = 1mA
500µs/Div
500µs/Div
Figure 28. Output Voltage Ripple;
VOUT = 18V, IOUT = 1mA
Figure 29. Output Voltage Ripple;
VOUT = 18V, IOUT = 20mA
VIN = 3.0V
VIN = 3.0V
1µs/Div
1µs/Div
VOUT(AC)
IOUT
1mA 20mA
VOUT(AC)
IOUT
200mV/Div
Figure 31. Load Transient Response OFF;
VCC = 3V, VOUT = 18V
200mV/Div
Figure 30. Load Transient Response ON;
VCC = 3V, VOUT = 18V
1mA 20mA
VOUT
VOUT
VIN = 1.5V
VIN = 1.5V
5ms/Div
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200mV/Div
VIN = 3.6V
200mV/Div
VIN = 3.6V
5ms/Div
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AS1344
Datasheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
The AS1344 features a current limiting circuitry, a fixed-frequency PWM architecture, power-OK circuitry, thermal protection, and an automatic powersave mode in a tiny package, and maintains high efficiency at light loads.
Figure 32. Block Diagram with Shutdown Disconnect Switch
L1
6.8µH
RV
Input Voltage
0.9V to 3.6V
8
7
2
6
VIN
SWOUT
POK
LX
0.3Ω
PMOS
VCC
PWM
Control
Sync Drive
Control
1 MHz
Spread
Spectrum
Ramp
Generator
Slope
Compensator
Shutdown
Control
Powersave
Shutdown
Powersave
Operation
Control
Output Voltage
5.5V to 42V
VOUT
R1
Current
Sense
Σ
AS1344
PWM –
Comp
–
1
9
0.9Ω
NMOS
+
EN
1.13V
–
VOUT
Good
+
Short
Delay
4
CIN
10µF
D1
VC
RC
COUT
10
–
gm Error
Amp
+
4.7µF
FB
CP2
CC
3 GND
1.25V
Ref
5
R2
PGND
Automatic powersave mode regulates the output and also reduces average current flow into the device, resulting in
high efficiency at light loads. When the output increases sufficiently, the powersave comparator output remains high,
resulting in continuous operation.
For each oscillator cycle, the power switch is enabled. A voltage proportional to switch current is added to a stabilizing
ramp and the resulting sum is delivered to the positive terminal of the PWM comparator.
The error amplifier compares the voltage at FB with the internal 1.25V reference and generates an error signal (VC).
When VC is below the powersave mode threshold voltage the automatic powersave-mode is activated and the hysteretic comparator disables the power circuitry, with only the low-power circuitry still active (total current consumption is
minimized).
When a load is applied, VFB decreases; VC increases and enables the power circuitry and the device starts switching.
In light loads, the output voltage (and the voltage at FB) will increase until the powersave comparator disables the
power circuitry, causing the output voltage to decrease again. This cycle is repeated resulting in low-frequency ripple at
the output.
POK Function
The POK output indicates if the output voltage is within 90% of the nominal voltage level. As long as the output voltage
is within regulation the open-drain POK output is high impedance. The POK output can be tied to any external voltage
up to a maximum of 5V via a pull-up resistance R3 (see Typical Application on page 12). If the output voltage drops
below 90% of the nominal voltage the POK pin is pulled to GND.
Note: It is important to consider that in shutdown mode the POK output is pulled to VCC in order to save current.
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AS1344
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
Shutdown and Output Discharge
A logic low on the EN pin shuts down the AS1344 and a logic high on the EN pin powers on the device. In shutdown
mode the supply current drops to below 3µA and the POK pin is set to high impedance to maximize battery life.
When the battery disconnect switch is used, the battery is disconnected from the output and the output is discharged
down to 0V. The time for fully discharging the output depends on the COUT and on the load.
Note: Pin EN should not be left floating. If the shutdown feature is not used, connect EN to VCC. The output will be
discharged during shutdown but the output also must be fully discharged before the device is enabled again.
Battery Disconnect
The AS1344 has an integrated PMOS switch that can be used to disconnect the battery during shutdown. The operation voltage of this switch is limited to 3.6V. When EN is high, the switch is closed and supplies the inductor. Due to the
RON resistance the efficiency is slightly lower if the battery disconnect switch is used.
PLOSS = IIN² x RON
(EQ 1)
Softstart Function
To limit the input current during startup a resistor RV can be connected between the pins VIN and VCC. For the correlation between the resistor value, the supply voltage and the startup time see Figure 33. For the correlation between
resistor value, the supply voltage and the peak current see Figure 34. Connect VIN directly to VCC (no resistor) to disable the softstart Function.
As an example some peak current and time values are listed at a given Rv in Table 4.
Table 4. Timing for Softstart @ VCC= 2.4V, COUT = 155µF,
RV [Ω]
0
1.0
1.5
2.0
2.4
3.0
IPEAK [A]
1.76
0.81
0.66
0.56
0.50
0.42
t [ms]
25
76
100
130
156
204
Figure 33. Startup Time; CIN = 150µF, COUT = 155µF
Figure 34. Peak Current; CIN = 10µF, COUT = 155µF
3.5
800
0 Ohm
1.0 Ohm
3
1.5 Ohm
1.5 Ohm
2.0 Ohm
600
2.4 Ohm
3.0 Ohm
500
400
300
200
2.0 Ohm
Peak Current (A)
Start-up Time (ms)
0 Ohm
1.0 Ohm
700
2.5
2.4 Ohm
3.0 Ohm
5.1 Ohm
2
1.5
1
0.5
100
0
0
1
1.4
1.8
2.2
2.6
3
3.4
1
Input Voltage (V)
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1.4
1.8
2.2
2.6
3
3.4
Input Voltage (V)
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AS1344
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Thermal Protection
To protect the device from short circuit or excessive power dissipation of the auxiliary NPNs, the integrated thermal
protection switches off the device when the junction temperature (TJ) reaches 140ºC (typ). When TJ decreases to
approximately 135ºC, the device will resume normal operation. If the thermal overload condition is not corrected, the
device will switch on and off while maintaining TJ within the range between 135 and 140ºC.
Setting Output Voltage
Output voltage can be adjusted by connecting a voltage divider between pins VOUT and FB (see Figure 35).
Figure 35. Typical Application
RV
L1
6.8µH
VCC = 0.9V
to 3.6V
C1
10µF
4
8
7
VIN
SWOUT
D1
6
VCC
VOUT = 18V
LX
COUT
4.7µF
R3
100kΩ
9
2
POK
On
1
Off
EN
VOUT
R1
2.2MΩ
AS1344
10
FB
R2
165kΩ
5
3
PGND
GND
The output voltage can adjusted by selecting different values for R1 and R2. For R2, select a value between 10k and
200kΩ.
Calculate R1 by:
V OUT
R 1 = R 2 ⋅ ⎛ -------------- – 1⎞
⎝ V FB
⎠
(EQ 2)
Where:
VOUT = 5.5V to 42V, VFB = 1.25V; VOUT > VIN
The input bias current of FB has a maximum value of 100nA which allows for large-value resistors. For less than 1%
error, the current through R2 should be 100 times the feedback input bias current (IFB). That’s why the feeback current
can be neglected in the calculation of VOUT.
Note: For the optimal operation condition the following ratio between VOUT and VIN should be used:
V OUT ÷ V IN ≤ 12
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AS1344
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
LED Power Supply Application
The AS1344 can also be used for driving LEDs. Just simply connect the LEDs between the pins VOUT and FB. (see
Figure 36).
Figure 36. LED Supply Application
RV
L1
6.8µH
VCC = 0.9V
to 3.6V
C1
10µF
4
8
7
VIN
SWOUT
6
VCC
D1
LX
COUT
4.7µF
R3
100kΩ
9
2
POK
On
1
Off
EN
VOUT
AS1344
10
FB
ILED
R2
100Ω
5
3
PGND
GND
The output voltage is adjusted automatically to the required voltage of the LEDs. This voltage depends on the forward
voltage (VF) of the used LEDs and the Feeback Voltage VFB.
Calculate VOUT by:
V OUT = V F ( I LED ) × n + V FB
(EQ 4)
Note: The brightness of the LEDs can directly be adjusted by setting the current ILED via the corresponding R2.
Calculate R2 by:
V FB
I LED = ---------R2
(EQ 5)
Where:
VFB = 1.25V
n .... number of LEDs
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AS1344
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Inductor Selection
For the external inductor, a 4.7µH or 6.8µH inductor will usually suffice. Minimum inductor size is dependant on the
desired efficiency and output current. Inductors with low core losses and small DCR at 1MHz are recommended. It’s
also recommended to choose an inductor which can handle at least 1.2A without saturating. The MOS6020 is a very
good choice because the DCR is quite small and the saturation current exceeds 1.2A. For space limiting applications
and input currents below 650mA the EPL2014 can be selected. Efficiency losses due to higher DCR should be considered. (see Figure 37 and Figure 38)
Table 5. Recommended Inductors
ISAT @ 20% drop Dimensions (L/W/T)
Part Number
L
DCR
EPL2014-472MLC
4.7µH
0.231Ω
0.65A
2.2x2.0x1.4mm
LPS3015-472MLC
4.7µH
0.200Ω
1.2A
3.1x3.1x1.5mm
LPS4018-682MLC
6.8µH
0.150Ω
1.3A
4.1x4.1x1.8mm
LPS5030-682ML_
6.8µH
0.099Ω
1.7A
4.88x4.88x3.0mm
MOS6020-682MLC
6.8µH
0.078Ω
1.56A
6.0x6.8x2.4mm
MOS6020-472MLC
4.7µH
0.050Ω
1.82A
6.0x6.8x2.4mm
Manufacturer
Coilcraft
www.coilcraft.com
Note: For the Efficiency measurements in Figure 37 and Figure 38 a MBR0540 diode was used for D1.
Figure 38. Efficiency Comparison of different
Inductors; VIN = 3.6V, VOUT = 18V
90
90
80
80
70
70
Efficiency (%)
Efficiency (%)
Figure 37. Efficiency Comparison of different
Inductors; VIN = 3V, VOUT = 18V
60
50
40
30
MOS6020 6.8µH
LPS5030 6.8µH
LPS4018 6.8µH
MOS6020 4.7µH
LPS3015 4.7µH
20
10
60
50
40
30
MOS6020 6.8µH
LPS5030 6.8µH
LPS4018 6.8µH
MOS6020 4.7µH
LPS3015 4.7µH
20
10
EPL2014 4.7µH
EPL2014 4.7µH
0
0
0.1
1
10
100
0.1
Output Current (mA)
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1
10
100
Output Current (mA)
Revision 1.05
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AS1344
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Capacitor Selection
A 10µF capacitor is recommended for CIN as well as a 4.7µF for COUT. Small-sized X5R or X7R ceramic capacitors
should be used as they retain capacitance over wide ranges of voltages and temperatures.
Output Capacitor Selection
Low ESR capacitors should be used to minimize VOUT ripple. Multi-layer ceramic capacitors are recommended since
they have extremely low ESR and are available in small footprints. A 4.7 to 10µF output capacitor is sufficient for most
applications. Larger values up to 22µF may be used to obtain extremely low output voltage ripple and improve transient response. The rated voltage of the capacitor should not be lower than the output voltage.
Table 6. Recommended Output Capacitors
Part Number
C
TC Code Rated Voltage
Dimensions (L/W/T)
GRM32DR71H335KA88B
3.3µF
X7R
50V
1210
GRM32ER71H475KA88
4.7µF
X7R
50V
1210
GRM31CR61E106KA12
10µF
X5R
25V
1206
C3225X5R1H335K
3.3µF
X5R
50V
1210
C3216X5R1E475K
4.7µF
X5R
25V
1206
C3225X5R1E106K
10µF
X5R
25V
1210
Manufacturer
Murata
www.murata.com
TDK
www.tdk.com
Input Capacitor Selection
Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Ceramic
capacitors are recommended for input decoupling and should be located as close to the device as is practical. A 10µF
input capacitor is sufficient for most applications. Larger values may be used for a better stabilization of the supply voltage.
Table 7. Recommended Input Capacitors
Part Number
C
GRM21BR60J106KE19
10µF
X5R
6.3V
0805
GRM188R60J106ME47
10µF
X5R
6.3V
0603
GRM21BR60J226ME39
22µF
X5R
6.3V
0805
C1608X5R0J106MB
10µF
X5R
6.3V
0603
C2012X5R0J226M
22µF
X5R
6.3V
0805
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TC Code Rated Voltage Dimensions (L/W/T)
Revision 1.05
Manufacturer
Murata
www.murata.com
TDK
www.tdk.com
15 - 19
AS1344
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Diode Selection
A Schottky diode must be used to carry the output current into the Cout and load during the NMOS switch-off time.
Note: Do not use ordinary rectifier diodes, since the slow recovery times will compromise efficiency.
The MBR0520 is a good choice because of the very low forward voltage and the extremely fast switching. If the output
voltage exceeds 20V the use of the PMEG4005 or the MBR0540 (40V Schottky diodes) is recommended. These
diodes are designed to handle an average forward current of 500mA. In applications with higher loads, the PMEG4010
or the MBRM140 should be used, due to the rated average forward current of 1A.
Table 8. Recommended Diodes
Part Number
Reverse Voltage
Forward Current
Package
MBR0540
40V
0.5A
SOD123
MBR0520
20V
0.5A
SOD123
PMEG4005
40V
0.5A
SOD123
PMEG4010
40V
1A
SOD123
MBRM140
40V
1A
SOD123
90
90
80
80
70
70
60
50
40
30
20
PMEG4010
10
MBR0520
MBR0540
Philips
www.nxp.com
ON Semiconductor
www.onsemi.com
Figure 40. Efficiency Comparison of different Diodes;
VIN = 3.6V, VOUT = 18V, L1 = 6.8µH
Efficiency (%)
Efficiency (%)
Figure 39. Efficiency Comparison of different Diodes;
VIN = 3V, VOUT = 18V, L1 = 6.8µH
Manufacturer
MCC
www.mccsemi.com
60
50
40
30
20
PMEG4010
10
MBR0520
MBR0540
PMEG4005
PMEG4005
0
0
0.1
1
10
100
0.1
Output Current (mA)
www.austriamicrosystems.com
1
10
100
Output Current (mA)
Revision 1.05
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AS1344
Datasheet - 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
10 Package Drawings and Markings
The devices are available in a TDFN-10 3x3mm package.
Figure 41. TDFN-10 3x3mm Package
D2
SEE
DETAIL B
A
D
D2/2
B
aaa C 2x
E
E2
E2/2
L
PIN 1 INDEX AREA
(D/2 xE/2)
K
PIN 1 INDEX AREA
(D/2 xE/2)
aaa C
N N-1
2x
e
TOP VIEW
e
b
(ND-1) X e
ddd
bbb
C
C A B
BTM VIEW
Terminal Tip
DETAIL B
A3
ccc C
A
C
0.08 C
SIDE VIEW
A1
SEATING
PLANE
Datum A or B
ODD TERMINAL SIDE
Symbol
A
A1
A3
L1
L2
aaa
bbb
ccc
ddd
eee
ggg
Min
0.70
0.00
Typ
0.75
0.02
0.20 REF
0.03
Max
0.80
0.05
0.15
0.13
0.15
0.10
0.10
0.05
0.08
0.10
Notes
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
Symbol
D BSC
E BSC
D2
E2
L
θ
K
b
e
N
ND
Min
1.60
1.35
0.30
0º
0.20
0.18
Typ
3.00
3.00
0.40
0.25
0.50
10
5
Max
2.50
1.75
0.50
14º
0.30
Notes
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2, 5
1, 2
1, 2, 5
Notes:
1. Figure 41 is shown for illustration only.
2. All dimensions are in millimeters; angles in degrees.
3. Dimensioning and tolerancing conform to ASME Y14.5 M-1994.
4. N is the total number of terminals.
5. The terminal #1 identifier and terminal numbering convention shall conform to JEDEC 95-1, SPP-012. Details of terminal #1 identifier are optional, but must be located within the zone indicated. The terminal #1 identifier may be either
a mold or marked feature.
6. Dimension b applies to metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip.
7. ND refers to the maximum number of terminals on side D.
8. Unilateral coplanarity zone applies to the exposed heat sink slug as well as the terminals
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AS1344
Datasheet - O r d e r i n g I n f o r m a t i o n
11 Ordering Information
The device is available as the standard products shown in Table 9.
Table 9. Ordering Information
Ordering Code
AS1344-BTDT
Marking
Description
Delivery Form
Package
ASR7
42V, DC-DC Boost Converter with
adjustable Softstart
Tape and Reel
TDFN-10 3x3mm
Note: All products are RoHS compliant and Pb-free.
Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect
For further information and requests, please contact us mailto:sales@austriamicrosystems.com
or find your local distributor at http://www.austriamicrosystems.com/distributor
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AS1344
Datasheet
Copyrights
Copyright © 1997-2009, austriamicrosystems 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.
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Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing
in its Term of Sale. austriamicrosystems 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.
austriamicrosystems 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 austriamicrosystems 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
austriamicrosystems 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 austriamicrosystems AG is believed to be correct and accurate. However,
austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to
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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
austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters
austriamicrosystems AG
Tobelbaderstrasse 30
A-8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
Fax: +43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact
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