STMicroelectronics STLED316S Datasheet
Annons
Annons
STLED316S
Serial-interfaced 6-digit LED controller with keyscan
Features
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LED driver with 14 outputs
(8 segments/6 digits)
40 mA load current capability for each segment
Output pins connected directly to the LEDs or can be open-drain
Key-scanning (8 x 2 matrix)
Low power consumption in standby mode
3-wire serial bus interface (CLK, STB,
DIN/DOUT)
8-step dimming circuit to control the overall display brightness
Single external resistor for output current setting
Inputs with Schmitt trigger give superior noise immunity
A single LED digit output (DIG1_LED) can be used to drive up to 8 discrete LEDs
8-step dimming circuit to control brightness of individual LEDs for LED digit
5.0 V (± 10%) for V
CC
Drives common-anode LED digits
Built-in power on reset and soft-start circuits
Available in SO24 package
-40 °C to 85 °C operating temperature range
Applications
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Set-top-boxes
White goods
Home appliances
DVD players and VCRs
Table 1.
Device summary
Part number
STLED316SMTR
Package
SO-24
SO-24
Description
The STLED316S is a compact LED controller and driver that interface microprocessors to LED displays through a serial 3-wire interface. It drives
LED connected in common anode configuration.
The STLED316S drives up to 48 discrete LEDs in
8 segment/6 digit configuration while functioning from a supply voltage of 5.0V. Additionally it can be used to drive 8 discrete LEDs which form a part of LED digit. The individual LEDs are wired as segments of a digit and brightness of these individual LEDs can be controlled digitally. The maximum segment current for the display digits is set through a single external resistor. Individual digits may be addressed and updated without rewriting the entire display.
Additionally it includes key scanning for an 8x2 key matrix which automatically scans a matrix of up to 16 switches. STLED316S supports numerictype displays and reduces the overall BOM costs through high integration. Also it provides ESD protection of greater than 4 kV HBM.
The LED controller/driver is ideal as a peripheral device to interface the display with a singlechip microcomputer.
Packaging
Tape and reel
January 2008 Rev 1 1/33 www.st.com
33
Contents
Contents
STLED316S
STLED316S functional and application diagram . . . . . . . . . . . . . . . . . . 3
STLED316S functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Low power mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Operating the device with 3.3 V interface voltages . . . . . . . . . . . . . . . . . . 9
Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Power consumption estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Power supply characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Dynamic switching characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Key-scan & display cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Key matrix and key-input data storage ram . . . . . . . . . . . . . . . . . . . . . 15
2/33
STLED316S
Contents
Display setting (maximum number of digits): . . . . . . . . . . . . . . . . . . . . . 19
Dimming setting (brightness levels): . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Key-scanning and display timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Serial communication format (reception) . . . . . . . . . . . . . . . . . . . . . . . . . 23
Serial communication format (transmission) . . . . . . . . . . . . . . . . . . . . . . 24
Switching characteristics waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Graph of ISET against RSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Power supply sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3/33
List of figures
List of figures
STLED316S
4/33
STLED316S
List of tables
List of tables
Seven segment display with dot point and common-anode LED panel . . . . . . . . . . . . . . . 11
= -40 to +85 °C, V
CC
A
= 5.0 V ± 10%, GND = 0 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
= 25 °C, f = 1 MHz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Dynamic switching characteristics
(TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0.0 V, typical values are at 25 °C) . . . . 16
CC
= 5.0 V ± 10%, GND = 0.0 V, Typical values are at 25 °C) . . . . 16
5/33
STLED316S functional and application diagram
1
STLED316S
STLED316S functional and application diagram
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The STLED 316S consists of the following blocks:
Current source
POR and soft-start
Interrupt generator
Serial interface
Digital logic blocks
Drivers
Figure 1.
STLED316S functional diagram
ISET
Current source
Output segments
VCC
POR
& soft-start
Internal reset
Interrupt generation
IRQ_N
SEG1/KS1
DIN/DOUT
CLK
STB
Serial
I/F
Internal clock generator
KEY1-KEY2
2
Command decoder
Display memory
(7 x 8)
Timing gen.
keysan & dimming
Keydata memory
(2 x 8)
8-bit output latch
7-bit shift register
8
7
SEG8/KS8
DIG1_LED
DIG7
DIG2
V
CC
(+5.0 V)
GND
(0 V)
6/33
STLED316S STLED316S functional and application diagram
Figure 2.
STLED316S application diagram
MCU
DIN / DOUT
IRQ_N
CLK
STB
STLED316S
ISET
RSET KEY1-KEY2
6 DIG2-DIG7
DIG1_LED
8
SEG1/KS1
-SEG8/KS8
LED 6-digit 7-segment (+dot-point) display panel
Keyscan
(8 x 2 matrix)
CS00014
7/33
Pin description
Figure 3.
STLED316S pin connection
STLED316S
8/33
Table 2.
Pin description
Pin number Symbol
1
2
3
DIN/DOUT
CLK
STB
4
5
6,7,8
IRQ_N
DIG1_LED
DIG2, DIG3,
DIG4
9 V
CC
10,11,12
DIG5, DIG6,
DIG7
Type
IN/OUT
IN
IN
OUT
OUT
OUT
PWR
OUT
Name and function
Output serial data at falling edge of the shift clock, starting from lower bit. Input serial data is clocked in at rising edge of the shift clock, starting from lower bit.
Reads serial data at rising edge, and outputs data at falling edge.
Initializes serial interface at rising or falling edge to make STLED316S wait for reception of command.
Data input after the falling edge of STB are processed as a command. While command data are processed, current processing is stopped, and the serial interface is initialized. While STB is high, instructions are ignored.
Interrupt output (active low) to interrupt the MCU when there is a key press
Single output LED used together with the 8 segments to drive up to 8 discrete LEDs
Digit output pins.
5.0 V ± 10% Core main supply voltage. Bypass to
GND through a 0.1 µF capacitor as close to the pin as possible.
Digit output pins.
STLED316S Pin description
Table 2.
Pin description (continued)
Pin number Symbol Type
13,14,15,16
17
18,19,20,21
SEG8/KS8 to
SEG5/KS5
GND
SEG4/KS4 to
SEG1/KS1
OUT
PWR
OUT
Name and function
Segment output pins (dual function as key source).
Connect this pin to system GND.
Segment output pins (dual function as key source).
22
23
24
KEY2
KEY1
ISET
IN
IN
IN
Key 2 input. Input data to these pins from external keyboard are latched at end of the display cycle
(maximum keyboard size is 8 x 2).
Key 1 input. Input data to these pins from external keyboard are latched at end of the display cycle
(maximum keyboard size is 8 x 2).
Segment current setting. Connect to GND through a resistor to set the peak segment current.
9/33
STLED316S functional description
3 STLED316S functional description
STLED316S
The STLED316S is a common-anode LED driver controller which can be used to drive red, green or blue LEDs as the current is adjustable through the external resistor. In the common anode configuration, the segment outputs sink the current from the cathodes while the digit outputs source the current to the anodes. The configurable output current can be used to drive LEDs with different current ratings (red, green or blue). The brightness of the whole display can be controlled through the serial interface as described later. The outputs can be connected together in parallel to drive a single LED. In this case, two parallel current sources of equal value drive a single LED. The external resistor value can be set accordingly to determine the desired output current thus controlling the display brightness.
Soft-start limits the inrush current during power-up. The display is blanked (LEDs are turned off or in high-Z state) on power-up.
3.1 Low power mode of operation
Upon initial power up or when not configured or when not used, the STLED316S will be in low power mode of operation wherein the current consumption drops to less than 1mA.
During this mode, the data configured is maintained as long as the supply voltage is still present (the contents of the internal RAM need the supply voltage to be present). Port configuration and output levels are restored when the STLED316S resumes normal operation. For minimum supply current in shutdown mode, logic inputs should be at GND or
V
CC
.
3.3
The interface is used to write configuration and display data to the STLED316S. The serial interface comprises of a shift register into which DIN is clocked on the rising edge of the
CLK when STB is low. When STB is low, falling transitions on CLK clock the data from the device to the microcontroller. The 8-bit data is decoded to determine and execute the command.
STB indicates to the device the start of communication when it goes low. DIN/DOUT pin is bi-directional. The data will be validated during positive pulse of the clock in both write/read modes. If the STB signal goes high before completing the data byte write to the device, the preceding data bits are ignored and the previous configuration remains intact.
Initial power up
On initial power-up, all control registers are reset, the display is blanked and the
STLED316S is in the low power mode. All the outputs are in high-impedance state at initial power-up. The DIN/DOUT is pulled high by an external pull-up resistor. The display driver has to be configured before the display can be used.
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STLED316S STLED316S functional description
Table 3.
Seven segment display with dot point and common-anode LED panel
3.5 Keyscan
The full keyscan is illustrated in the another section of the datasheet. One diode is required per key switch. The keyscan circuit detects any combination of keys being pressed.
3.6 Discrete LED outputs
The STLED316S can be used to drive up to 8 discrete LEDs. The single LED output acts like a digit driver output and can be wired-up with 8 segment outputs to drive up to 8 different discrete LEDs. Physical connections from the LED output as well as the segment outputs must be made to drive the discrete LEDs in the desired manner. The discrete LEDs may be needed to indicate the “Power”, “Standby” status (for example). Also it is possible to separately control the brightness of each single LED.
3.7 Power on reset and soft-start
The device integrates an internal power-on-reset circuit which initializes the digital logic upon power up. The soft-start circuit limits the inrush current and high peak current during power-up. This is done by delaying the input circuit’s response to the external applied voltage. During soft-start, the input resistance is higher which lowers the in-rush current when the supply voltage is applied.
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STLED316S functional description STLED316S
The constant current capability is up to 40 mA per output segment and is set for all the outputs using a single external resistor. When acting as digit drivers, the outputs source current to the display anodes. When acting as segment drivers, the LED outputs sink current from the display cathodes. The outputs are high impedance when not being used as digit or segment drivers.
Each port configured as a LED digit driver behaves as a digitally-controlled constant current sink. The LED drivers are suitable for both discrete LEDs and common anode (CA) numeric
LED digits. When fully configured as a LED driver, the STLED316S controls up to 8 LED segments in a single digit with 8-step logarithmic brightness control for the digits. A single resistor sets the maximum segment current for all the segments, with a maximum of 40mA per segment. The STLED316S drives any combination of discrete LEDs and CA digits for numeric displays.
The recommended value of R
SET
is the minimum allowed value, since it sets the display driver to the maximum allowed segment current. R
SET
can be a higher value to set the segment current to a lower maximum value where desired. The user must also ensure that the maximum current specifications of the LEDs connected to the drivers are not exceeded.
The brightness of the individual digits in the display panel can be controlled separately.
3.9 Interrupt
The device includes an active low level IRQ_N pin to the microprocessor. The STLED316S generates an interrupt when a key is pressed.
3.10 Operating the device with 3.3 V interface voltages
The device can detect the input voltage levels reference to 3.3 V from the main controller chip as long as the V
IL
and V
IH
specifications of the STLED316S are met. If the input voltage to STLED316S is greater than 2.9 V, the STLED316S will recognize the signal level as a valid high and if the input voltage is lower than 1.75 V, it will be recognized as a valid low level.
For the output signals from the device like DOUT and IRQ_N, the signal level depends on the external supply to which the external pull up resistor is connected to. Thus this eliminates the use of any level shifter between the main controller and the STLED316S.
12/33
STLED316S Maximum rating
Stressing the device above the rating listed in the “Absolute maximum ratings” table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE program and other relevant quality documents.
Table 4.
Symbol
Absolute maximum ratings (all voltages are referenced to GND)
Parameters Values
V
T
V
P
T
CC
V
T
I
D
A
J
STG
T
L
ESD
Supply voltage to ground
Logic input voltage
Power dissipation
(1)
Operating ambient temperature
Junction temperature
Storage temperature
Lead temperature (10 sec)
Electrostatic discharge voltage on all pins
(2)
Human body model
1.
De-rate at -9.6 mW/°C at T
A
= 25°C or higher
2.
In accordance with the JEDEC standard
-0.5 to +7.0
-0.5 to V
CC
+0.5
1200
-40 to 85
150
-65 to +150
300
-4 to +4
Unit
V
V mW
°C
°C
°C
°C kV
Table 5.
Symbol
T thJC
Thermal data
Parameter Min Typ
Thermal resistance junction-ambient 75
Max Unit
°C/W
13/33
Recommended operating conditions
5 Recommended operating conditions
5.1
STLED316S
DC electrical characteristics
Table 6.
DC electrical characteristics
(T
A
= -40 to +85 °C, V
CC
= 5.0 V ± 10%, GND = 0 V)
Parameter Test conditions Min Typ Max Unit Symbol
V
CC
Logic supply voltage
V
V
IH
IL
High level input voltage
Low level input voltage
High level guaranteed digital pins
Low level guaranteed digital pins
V
IN
= V
CC
or GND I
IH
V
, I
IL
HYS
Input current
Hysteresis voltage
(DIN, CLK, STB pins)
V
OL(DOUT)
I
OLEAK
Low level output voltage
Driver leakage current
I
I
I
SEG
DIG
TOLSEG
R
SET
DOUT, I
OL2
Drivers off
= 4 mA
Segment drive LED sink current
Digit drive LED source current
V
LED
= 2.5 V
V
DIGIT
= V
CC
– 1.0
V
DIGIT
= V
CC
– 1.0
Segment drive current matching
V
CC
V
LED
= 5.0 V, T
A
= 2.5 V
= 25 °C
External current setting reference resistor
(precision = ±1% tolerance)
I
SEG
= 40 mA
4.5
0.57
V
CC
0
-2
0.9
-30
240
5.0
1.05
-40
320
3
360
5.5
V
CC
0.3V
CC
2
1.2
0.4
-140
-50
400
V
V
V
µA
V
V
µA mA mA
%
Ω
14/33
STLED316S
5.2
Recommended operating conditions
Power consumption estimation
Each port of the STLED316S can sink a maximum current of 40 mA into an LED with a
4.4 V forward voltage drop when operated from a supply voltage of 5.0 V. The minimum voltage drop across the internal LED drivers is thus 5.0 - 4.4 = 0.6 V. The STLED316S can sink 8 x 40 = 320 mA when all outputs are operating as LED segment drivers at full current.
On a 5.0 V supply, a STLED316S dissipates (5.0 V - 4.4 V) x 320 mA = 192 mW when driving 8 of these 4.4 V forward voltage drop LEDs at full current. If the application requires high drive current, consider adding a series resistor to each LED to drop excessive drive voltage off-chip.
If the forward voltage of the LED is lesser than 4.4 V (say 2.4 V), then the maximum power dissipation of STLED316S when all segments are turned on will be ( 5 - 2.4) V x
320 mA = 832 mW. To lower the power dissipation, consider adding a small series resistor in the supply. Another alternative is to increase the value of the R
SET
to lower the current of the LEDs from 40 mA to say 30 or 20 mA.
The efficiency will be the power consumption in the LEDs divided by the input power consumed.
Efficiency = V diode
x I diode
/ V
CC
x I
CC
As an example, consider LED with forward voltage of V
F
= 2.4V, I peak
= 40 mA,
V
CC (max)
= 5.5 V, N = number of segments = 8 (max), D = duty cycle = 15/16,
Power dissipation, P
D (max)
= 5 mA x 5.5 V + (5.5 - 2.4) V x (15/16) x 40 mA x 8 = 27.5 + 780
= 807.5 mW. To lower this value, add a series resistor with the supply.
5.3 Capacitance
Table 7.
Symbol
C
IN
Capacitance (T
A
= 25 °C, f = 1 MHz)
Parameter Test conditions
Input capacitance
Min Typ Max Unit
15 pF
5.4 Power supply characteristics
Table 8.
Symbol
I
STBY
I
CC
Power supply characteristics (T
A
= -40 to +85 °C)
Parameter Test conditions Min.
Typ.
Max.
Unit
Quiescent power supply current
V
CC
= 5.5 V,
All inputs = V
CC or GND
Operating power supply current
(display ON)
All segments ON, all digits scanned, intensity set to full, internal oscillator, no display load connected
50
10
1000 µA
15 mA
15/33
Recommended operating conditions
5.5
STLED316S
Dynamic switching characteristics
Table 9.
t
PLZ
Dynamic switching characteristics
(T
A
= -40 to +85 °C, V
25 °C)
CC
= 5.0 V ± 10%, GND = 0.0 V, typical values are at
Parameter Test conditions Min.
Typ.
Max.
Unit Symbol f
OSC f
MAX
Internal oscillation frequency
Clock (CLK) frequency
Propagation delay
Duty = 50%
CLK to DOUT
R
L
= 10 KΩ, C
L
= 15 pF
400
1
500 600 kHz
MHz
300 ns t
PZL
100 ns
Table 10.
Timing characteristics
(T
A
= -40 to +85 °C, V
25 °C)
CC
= 5.0 V ± 10%, GND = 0.0 V, Typical values are at
Symbol Parameter Test conditions Min.
Typ.
Max.
Unit
PW
CLK
PW
STB t
SETUP t
HOLD
Clock pulse width
Strobe pulse width
Data setup time
Data hold time
400
1
100
100 ns
µs ns ns t
CLK-STB
Clock-strobe time
CLK rising edge to STB rising edge
1 µs
Table 11.
ESD performance
Symbol Parameter
ESD JEDEC standard (all pins)
Test conditions
HBM
Min.
Typ.
Max.
Unit
±4 kV
16/33
STLED316S
6 Key-scan & display cycle
Key-scan & display cycle
The display RAM stores the data transmitted from an external device to the STLED316S
through the serial interface. Refer to Section 9: Key-scanning and display timing on page 25
for a pictorial representation.
The grid and segment outputs are controlled by the display output module. The entire grid will be turned off on channel 1/16 and 16/16 meaning that the first channel and last channel are off. This is referred to as blanking time.
During the keyscan time (first cycle from timing generator), the entire grid is turned off and only the segments are enabled one by one (seg0 to seg7). The segment on time is 64 µs.
During the LED discrete time (second cycle), the data present on the internal LED buffer is checked. If the data is present, then the brightness setting of each LED in the brightness control register is checked. Then each segment will be enabled or disabled based on the register value. In this duration, the grids 1 to 6 are turned off. The grid corresponding to LED digit is turned on. The LED on duty cycle is 14/16. If the LED/seg1 brightness is 12/16, it means that the segment1 OFF time is 12/16 and on time is 2/16.
During 7-segment display time (3 rd
cycle to 8 th
cycle), the display status is checked whether it is ON or OFF. If display is ON, then the dimming settings are checked from the configuration register for the grid (it may be common dimming setting or individual dimming setting for each digit). The minimum turn on time is 1/16 and maximum turn on time is 14/16.
The blanking time is valid before the turning on and turning off of the grid. The blanking interval is 32 µs. This will continue until the maximum number of digits configured in the register. Once the full cycle is complete, the keyscan cycle will start again.
If the display is not turned on, then the timing generation will immediately go to the key scan mode.
Initial:
All the segments and grids are turned off.
During operation:
1. Turn on segment (keyscan) one by one. On time duration is 64 µs.
2. Check the data present in LED register. If data is present, turn on the respective LED grid and segments.
3. Check the display on. If display is turned on, then enable the grid one by one from grid
1 to grid 6 (maximum) and turn on segments.
17/33
Key matrix and key-input data storage ram
7 Key matrix and key-input data storage ram
STLED316S
During the key scan cycle all the grids are turned off. The first segments turn on is 64 µs.
The key1 and key2 signals will be sampled after 60 µs. The two signals latch into the internal key buffer. The same applies for other segments.
This key buffer compares the data with the previous key status. If any changes are seen in the buffer values, then the IRQ_N is asserted. The IRQ_N signal is active low (level). This
IRQ_N signal will be cleared at the end of reading the key buffer (end of byte transfer). The key buffer must be completely read before the IRQ_N is cleared.
The key matrix is of 8 x 2 configuration, as shown below:
Figure 4.
Key matrix
18/33
The data of each key are stored as illustrated below, and are read by the appropriate read command, starting from the least significant bit.
1
st
byte
KEY1
SEG1/KS1
LSB
2
nd
byte
KEY1
SEG2/KS2
KEY1
SEG3/KS3
KEY1
SEG4/KS4
KEY1
SEG5/KS5
KEY1
SEG6/KS6
KEY1
SEG7/KS7
KEY1
SEG8/KS8
MSB
KEY2
SEG1/KS1
LSB
KEY2
SEG2/KS2
KEY2
SEG3/KS3
KEY2
SEG4/KS4
KEY2
SEG5/KS5
KEY2
SEG6/KS6
KEY2
SEG7/KS7
KEY2
SEG8/KS8
MSB
The initial key buffer value is “00”. During operation, the buffer values will change depending upon the values of the key-press.
STLED316S
8 Commands
Commands
Command sets the display mode and the status of the LED driver. The first byte input to the
STLED316S through the DIN input after the STB goes low is regarded as a command. If
STB is set high while commands/data are transmitted, serial communication is initialized, and the commands/data being transmitted are invalid (however, the commands/data already transmitted remain valid).
MSB 8 MSB 7 MSB6 MSB5 LSB4 LSB3 LSB2 LSB1
Description: LSB 3 -1
MSB5 and LSB4
→
MSB
→
‘1’ fixed address
MSB 7
→
‘1’ Read command
MSB 8
→
The following bytes are either configuration data or display data.
During the write command, the control flag display on and auto increment address are latched into the internal control flag register. The default value is ‘0’ for display on control register implying that the display is off. The user must turn on the display to view the display memory. Similarly the auto increment address mode is enabled by default. If the user desires to read from a particular address location, the user can fix the address pointer.
Display on:
MSB 8 x
Display off:
MSB 7
0
MSB6
X
MSB5
0
LSB4
1
LSB3
1
MSB 8 x
MSB 7
0
MSB6
X
MSB5
0
LSB4
1
Use these two commands to turn the display ‘ON’ and ‘OFF’.
LSB3
1
LSB2
0
LSB2
1
LSB1
1
LSB1
0
19/33
Commands STLED316S
MSB 8 MSB 7 MSB6 MSB5 LSB4
Description: LSB 3 -1
MSB5 and LSB4 →
MSB 6 →
‘1’ fixed address
MSB 7 →
‘1’ Read command
MSB 8 →
Use the page 0x01 to read the LED data and key data.
LSB3 LSB2 LSB1
Table 12.
Read command
Address
00
01
02
Function
LED data (optional)
Key data byte1
Key data byte2
Set flag for key1 and key2 to ensure that the user reads from the particular key. When reading the key data from the memory, the IRQ_N will be automatically cleared signifying that the end of the 8 th
bit was transmitted correctly.
If the IRQ_N is asserted by the last eight keys, then the user reads the key data (one byte only by reading the first byte). In this case, the IRQ_N will remain active until the second byte is read. When the user uses the read key to read the LED and key data, first the user must choose the address (default address location is 0x00) after which the address will increment only by 3 addresses (maximum).
20/33
This section describes how to program and read the configuration of the device.
Configuration data comprises of the display setting, dimming setting, display on/off and fixed
STLED316S Commands address/auto increment. The address pointer will indicate the configuration location and write signal writes the configuration data into the respective location.
The memory block is split into two page locations. One is for the 7-segment brightness configuration memory and the other is for the LED (discrete) configuration memory. The configuration memory address starts from 0x00 to 0x07. The configuration page address is
“10” and “11”.
Initial Value:
Table 13.
Memory page mapping
Memory page
11
11
11
11
10
10
10
10
Address
00
01
02
03
00
01
02
03
Value
0xFB
0x00
0x00
0x00
0x00
0x00
0x00
0x00
Description: Address 0x00; page 0x10
LSB 0 – 2 →
LSB3 MSB 4
→
→
→
'01' is reserved
→
'10' is reserved
MSB 5 – 7 →
(discrete)
Default is constant brightness control with 14/16 pulse width (for maximum brightness).
Page 0x10 - address 0x01 to 0x03 is for the variable brightness control value for 7 segments:
Table 14.
Digit address mapping
Address
0x01
0x02
0x03
MSB
Digit 2
Digit 4
Digit 6
LSB
Digit 1
Digit 3
Digit 5
Default is constant brightness control with 14/16 pulse width.
Page0x11 - address 0x00 to 0x03 is for the variable brightness control value for LED
(discrete)
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Commands
8.3.1
STLED316S
Table 15.
LED address mapping
Address
0x00
0x01
0x02
0x03
MSB
LED/ Seg 2
LED/ Seg 4
LED/ Seg 6
LED/ Seg 8
LSB
LED/ Seg 1
LED/ Seg 3
LED/ Seg 5
LED/ Seg 7
Default is constant brightness control with 14/16 pulse width.
During normal operation, the user defined value will be stored in the respective location.
Display setting (maximum number of digits):
The 3-bit values corresponding to selection of number of digits of display are shown below:
000: 1 digit 8 segments
001: 2 digits 8 segments
010: 3 digits 8 segments
011: 4 digits 8 segments
100: 5 digits 8 segments
101: 6 digits 8 segments
Select the number of digits by writing the value in page 0x10 and the address 0x00 in LSB2 to LSB0.
The 4-bit values corresponding to different brightness levels are shown below:
0000: pulse width is 1/16
0001: pulse width is 2/16
0010: pulse width is 4/16
0011: pulse width is 10/16
0100: pulse width is 11/16
0101: pulse width is 12/16
0110: pulse width is 13/16
0111: pulse width is 14/16
Set the dimming timing (write into respective address location from 0x00 to 0x03; page 0x10
& 0x11).
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STLED316S Commands
The display memory stores the display data and sends to the LED when the display is on.
The address pointer, memory page and write signal indicates to this block the location to write the data. This block will manage the address pointer. When the user writes a first byte, the address increments by one if in auto-increment mode, else the address pointer remains in the same location. The initial address is latched during the write/read command into the address pointer. The display memory (7-segment/LED) is directly mapped into the display segments. The user can access only one bank at a time in both the read and write modes.
The memory block is split into 4 pages.
Table 16.
Memory page address
Page 1
7 segment memory
Addr 0x00 to 0x05
(40 bit)
Page 2
LED Display
Addr 0x00
(8 bit)
Page 3
Page 4
7 segment brightness setting
LED brightness setting
Addr 0x00 to 0x03
(32bit)
Addr 0x00 to 0x03
(32bit)
7-segment display memory page 0x00:
Table 17.
7-segment display address
Address
0x00
0x01
0x02
0x03
0x04
0x05
Data
0x00
0x00
0x00
0x00
0x00
0x00
LED display memory page 0x01:
Table 18.
LED display address
Address
0x00h
Data
0x00h
Initial memory:
Default memory value is “00” in all locations.
During operation:
User defined value in these locations.
When the user wants to read the data from a particular location, the user sends the address page through read command and chooses the mode of the address pointer (fixed or auto).
In this case, the user can access the whole memory area in that particular page (maximum
0 x 05).
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Commands STLED316S
The display RAM stores the data transmitted from an external device to the STLED316S through the serial interface; addresses are as follows, in 8-bits unit:
Seg1
00 H
L
01 H
L
02 H
L
03 H
L
04 H
L
05 H
L
Seg4
00 H
U
01 H
U
02 H
U
03 H
U
04 H
U
05 H
U
Seg8
DIG2
DIG3
DIG4
DIG5
DIG6
DIG7 b0
XX H
L b3 b4 b7
XX H
U
“0” in memory means GND on output; “1” in memory means V
CC
on output.
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STLED316S
9 Key-scanning and display timing
Key-scanning and display timing
During the first cycle, the 16 channels are used for the keyscan. The keyscan duration is made up of 64 µs. The second cycle is used for the display of the LED (discrete). The maximum time is 512µs and the 3 rd
-8 th
cycles are used for the 7-segment display. The number of cycles will increase or decrease depending upon the user configuration.
By default, the configuration is made up of 4 cycles. If any data is written to the discrete
LED, only then the 2 nd
cycle is valid. Otherwise the 7-segment moves from 2 nd
-7 th
cycle.
This is a continuous operation. During the normal operation, the user cannot control or stop the timing generation.
One cycle of key scanning consists of one frame, and data of 8 x 2 matrices are stored in the RAM.
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Key-scanning and display timing
9.1
STLED316S
Serial communication format (reception)
The figure below shows the “reception” by STLED316S for command/data write sequence.
The STB must be low for 1 µs before the first and last clock rise. The minimum time the STB must remain low is 9 µs.
The maximum clock frequency is 1 MHz with a duty cycle of 50%. Data set-up and hold time must be 100 ns.
Figure 5.
Serial communication format (reception)
If data are contiguous
STB b0 b1 b2 b6 b7
DIN
CLK
2 3
CS15561
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STLED316S Key-scanning and display timing
The figure below shows the “transmission” from STLED316S for data read sequence.
Figure 6.
Serial communication format (transmission)
If data are contiguous
STB
DIN b0 b1 b2 b6 b7
CLK
2 3
Note:
CS15561
Because the DIN/DOUT pin in a bi-directional pin, it is recommended to connect an external pull-up resistor to thi s pin (1 KΩ to 10 KΩ).
No minimum wait time is needed to read the data from the device. The STLED316S will output the data about 250 ns after the 8 th
clock pulse’s falling edge. It is therefore suggested that the host must release the bus within 100ns after clocking the last bit on the 8 th
clock pulse. The STLED316S is able to clock out the valid data on the immediate falling edge of the CLK without missing any clock cycle.
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Switching characteristics waveform
10 Switching characteristics waveform
Figure 7.
Switching characteristics waveform
STB
CLK
DIN
DOUT
Sn/Gn
PW
CLK
PW
CLK t
SETUP t
HOLD
90%
10% t
THZ t
PZL t
PLZ t
TZH t
CLK-STB
PW
STB
STLED316S
CS15562
28/33
STLED316S
11.1 Graph of ISET against RSET
Figure 8.
Graph of ISET against RSET
Application information
RSET
29/33
Application information STLED316S
11.2 Power supply sequencing
Proper power-supply sequencing is advised for all CMOS devices. It is recommended to always apply V
CC or control pins.
before applying any signals to the input/output
Figure 9.
STLED316S application diagram
VCC
C1
C2
R2 R1
GND
VCC
6
MCU
CLK
STB
DIN / DOUT
IRQ_N
ISET
STLED316S
SEG1/KS1
-SEG8/KS8
DIG2-DIG7
DIG1_LED
D1 D2 D3 D4 D5 D6 D7 D8
RSET
GND
KEY1-KEY2
GND
R3
R4
Keyscan
(8 x 2 matrix)
LED 6-digit 7-segment (+dot-point) display panel
CS00018
Table 19.
Part list
Resistors
RSET = external resistor for current setting
R1 = 1-10 K Ω
DIN/DOUT external pull-up resistor
R2 = 1-10 K
Ω IRQ_N external pull-up resistor
R3-R4 = 10 K Ω external key-matrix pull-down resistors
Capacitors
C1 = 33 µF (25V) electrolytic
C2 = 0.01- 0.1 µF
(25 V) ceramic
Diodes
D1-D8 = 1N4148
Supply V
VCC = 5 V ± 10%
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STLED316S
12 Package mechanical data
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK
® packages. These packages have a Lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com.
Figure 10.
SO-24 package outline
0070769C
E e
C
D
A
A1
B
L k
H h ddd
Table 20.
SO-24 package mechanical data millimeters
Symbol
Min Typ Max
2.35
0.1
0.33
0.23
15.20
7.4
10.00
0.25
0.4
0 °
1.27
2.65
0.30
0.51
0.32
15.60
7.6
10.65
0.75
1.27
8 °
0.100
Min
0.093
0.004
0.013
0.009
0.598
0.291
0.394
0.010
0.016
0 ° inches
Typ
0.050
31/33
Max
0.104
0.012
0.020
0.013
0.614
0.299
0.419
0.030
0.050
8 °
0.004
Revision history
Table 21.
Document revision history
Date Revision
9-Jan-2008 1 Initial release.
Changes
STLED316S
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STLED316S
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