ST STLED316S User Manual

Serial-interfaced 6-digit LED controller with keyscan
Features
LED driver with 14 outputs
(8 segments/6 digits)
40 mA load current capability for each segment
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
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
Set-top-boxes
White goods
Home appliances
DVD players and VCRs

Table 1. Device summary

CC
STLED316S
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.
Part number Package Packaging
STLED316SMTR SO-24 Tape and reel
January 2008 Rev 1 1/33
www.st.com
33
Contents STLED316S
Contents
1 STLED316S functional and application diagram . . . . . . . . . . . . . . . . . . 3
2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 STLED316S functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Low power mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2 Serial interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Initial power up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.4 Display types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.5 Keyscan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.6 Discrete LED outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.7 Power on reset and soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.8 LED drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.9 Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.10 Operating the device with 3.3 V interface voltages . . . . . . . . . . . . . . . . . . 9
4 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1 DC electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.2 Power consumption estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.3 Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.4 Power supply characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.5 Dynamic switching characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.6 Timing characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.7 ESD performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 Key-scan & display cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7 Key matrix and key-input data storage ram . . . . . . . . . . . . . . . . . . . . . 15
8 Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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STLED316S Contents
8.1 Write command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.2 Read command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.3 Device configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.3.1 Display setting (maximum number of digits): . . . . . . . . . . . . . . . . . . . . . 19
8.3.2 Dimming setting (brightness levels): . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.4 Display memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9 Key-scanning and display timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.1 Serial communication format (reception) . . . . . . . . . . . . . . . . . . . . . . . . . 23
9.2 Serial communication format (transmission) . . . . . . . . . . . . . . . . . . . . . . 24
10 Switching characteristics waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
11 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11.1 Graph of ISET against RSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11.2 Power supply sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
11.3 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
12 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
13 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
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List of figures STLED316S
List of figures
Figure 1. STLED316S functional diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. STLED316S application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 3. STLED316S pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 4. Key matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 5. Serial communication format (reception) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 6. Serial communication format (transmission). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 7. Switching characteristics waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 8. Graph of ISET against RSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 9. STLED316S application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 10. SO-24 package outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
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STLED316S List of tables
List of tables
Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 3. Seven segment display with dot point and common-anode LED panel . . . . . . . . . . . . . . . 11
Table 4. Absolute maximum ratings (all voltages are referenced to GND). . . . . . . . . . . . . . . . . . . . 13
Table 5. Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 6. DC electrical characteristics
(T
= -40 to +85 °C, VCC= 5.0 V ± 10%, GND = 0 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 7. Capacitance (T
Table 8. Power supply characteristics (TA = -40 to +85 °C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 9. Dynamic switching characteristics
Table 10. Timing characteristics
Table 11. ESD performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 12. Read command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 13. Memory page mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 14. Digit address mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 15. LED address mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 16. Memory page address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 17. 7-segment display address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 18. LED display address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 19. Part list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 20. SO-24 package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 21. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
A
(TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0.0 V, typical values are at 25 °C) . . . . 16
(TA = -40 to +85 °C, V
= 25 °C, f = 1 MHz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
A
= 5.0 V ± 10%, GND = 0.0 V, Typical values are at 25 °C) . . . . 16
CC
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STLED316S functional and application diagram STLED316S

1 STLED316S functional and application diagram

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
DIN/DOUT
CLK
STB
KEY1-KEY2
Current
source
Internal clock
generator
2
Serial
I/F
Output
segments
VCC
Command
decoder
Display memory
(7 x 8)
Timing gen.
keysan & dimming
Keydata memor y
(2 x 8)
POR
&
soft-start
8-bit
output
latch
7-bit shift
register
V
CC
(+5.0 V)
Internal
reset
GND (0 V)
8
7
Interrupt
generation
IRQ_N
SEG1/KS1
SEG8/KS8
DIG1_LED
DIG7
DIG2
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STLED316S STLED316S functional and application diagram

Figure 2. STLED316S application diagram

6
MCU
DIN / DOUT
IRQ_N
RSET
CLK
STB
ISET
STLED316S
KEY1-KEY2
Keyscan
(8 x 2 matrix)
8
SEG1/KS1
-SEG8/KS8
DIG2-DIG7
DIG1_LED
LED 6-digit 7-segment (+dot-point) display panel
CS00014
7/33
Pin description STLED316S

2 Pin description

Figure 3. STLED316S pin connection

Table 2. Pin description

Pin number Symbol Type Name and function
Output serial data at falling edge of the shift clock,
1 DIN/DOUT IN/OUT
2CLK IN
3STB IN
4IRQ_NOUT
5 DIG1_LED OUT
6,7,8
9V
DIG2, DIG3,
DIG4
CC
OUT Digit output pins.
PWR
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
5.0 V ± 10% Core main supply voltage. Bypass to GND through a 0.1 µF capacitor as close to the pin as possible.
10,11,12
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DIG5, DIG6,
DIG7
OUT Digit output pins.
STLED316S Pin description
Table 2. Pin description (continued)
Pin number Symbol Type Name and function
SEG8/KS8
13,14,15,16
17 GND PWR Connect this pin to system GND.
18,19,20,21
22 KEY2 IN
23 KEY1 IN
to
SEG5/KS5
SEG4/KS4
to
SEG1/KS1
OUT Segment output pins (dual function as key source).
OUT Segment output pins (dual function as key source).
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).
24 ISET IN
Segment current setting. Connect to GND through a resistor to set the peak segment current.
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STLED316S functional description STLED316S

3 STLED316S functional description

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

3.2 Serial interface

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.

3.3 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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