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
■ 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
■
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.
= 5.0 V ± 10%, GND = 0.0 V, Typical values are at 25 °C) . . . . 16
CC
5/33
STLED316S functional and application diagramSTLED316S
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
6/33
STLED316SSTLED316S 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 descriptionSTLED316S
2 Pin description
Figure 3.STLED316S pin connection
Table 2.Pin description
Pin numberSymbolTypeName and function
Output serial data at falling edge of the shift clock,
1DIN/DOUTIN/OUT
2CLK IN
3STB IN
4IRQ_NOUT
5DIG1_LEDOUT
6,7,8
9V
DIG2, DIG3,
DIG4
CC
OUTDigit 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
8/33
DIG5, DIG6,
DIG7
OUTDigit output pins.
STLED316SPin description
Table 2.Pin description (continued)
Pin numberSymbolTypeName and function
SEG8/KS8
13,14,15,16
17GNDPWRConnect this pin to system GND.
18,19,20,21
22KEY2IN
23KEY1IN
to
SEG5/KS5
SEG4/KS4
to
SEG1/KS1
OUTSegment output pins (dual function as key source).
OUTSegment 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).
24ISETIN
Segment current setting. Connect to GND through a
resistor to set the peak segment current.
9/33
STLED316S functional descriptionSTLED316S
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.
10/33
Loading...
+ 23 hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.