STMICROELECTRONICS STLED316S_08

STLED316S
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 VCC
■
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.
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.
Device summary
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
4
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
Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1
5
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
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
2/33
STLED316S
Contents
8.1
Write command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.2
Read command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.3
Device configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.4
9
8.3.1
Display setting (maximum number of digits): . . . . . . . . . . . . . . . . . . . . . 19
8.3.2
Dimming setting (brightness levels): . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Display memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
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
3/33
List of figures
STLED316S
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
4/33
STLED316S functional diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
STLED316S application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
STLED316S pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Key matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Serial communication format (reception) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Serial communication format (transmission). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Switching characteristics waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Graph of ISET against RSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
STLED316S application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
SO-24 package outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
STLED316S
List of tables
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
Table 15.
Table 16.
Table 17.
Table 18.
Table 19.
Table 20.
Table 21.
Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Seven segment display with dot point and common-anode LED panel . . . . . . . . . . . . . . . 11
Absolute maximum ratings (all voltages are referenced to GND). . . . . . . . . . . . . . . . . . . . 13
Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
DC electrical characteristics
(TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Capacitance (TA = 25 °C, f = 1 MHz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Power supply characteristics (TA = -40 to +85 °C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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
Timing characteristics
(TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0.0 V, Typical values are at 25 °C) . . . . 16
ESD performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Read command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Memory page mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Digit address mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
LED address mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Memory page address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7-segment display address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
LED display address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Part list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
SO-24 package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5/33
STLED316S functional and application diagram
1
STLED316S
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
Current
source
Output VCC
segments
POR
&
soft-start
Internal
reset
Serial
I/F
Internal clock
generator
Display memory
(7 x 8)
IRQ_N
SEG1/KS1
Command
decoder
DIN/DOUT
CLK
STB
Interrupt
generation
8
8-bit
output
latch
SEG8/KS8
Timing gen.
keysan & dimming
DIG1_LED
Keydata memory
(2 x 8)
KEY1-KEY2
7-bit
shift
register
DIG7
7
2
V
CC
(+5.0 V)
6/33
GND
(0 V)
DIG2
STLED316S
STLED316S functional and application diagram
Figure 2.
STLED316S application diagram
6
DIG2-DIG7
CLK
LED 6-digit 7-segment (+dot-point) display panel
DIG1_LED
STB
MCU
STLED316S
DIN / DOUT
IRQ_N
8
ISET
RSET
SEG1/KS1
-SEG8/KS8
KEY1-KEY2
Keyscan
(8 x 2 matrix)
CS00014
7/33
Pin description
2
8/33
STLED316S
Pin description
Figure 3.
STLED316S pin connection
Table 2.
Pin description
Pin number
Symbol
Type
Name and function
1
DIN/DOUT
IN/OUT
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.
2
CLK
IN
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.
3
STB
IN
4
IRQ_N
OUT
Interrupt output (active low) to interrupt the MCU
when there is a key press
5
DIG1_LED
OUT
Single output LED used together with the 8 segments
to drive up to 8 discrete LEDs
6,7,8
DIG2, DIG3,
DIG4
OUT
Digit output pins.
9
VCC
PWR
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
DIG5, DIG6,
DIG7
OUT
Digit output pins.
STLED316S
Pin description
Table 2.
Pin description (continued)
Pin number
Symbol
Type
Name and function
13,14,15,16
SEG8/KS8
to
SEG5/KS5
OUT
Segment output pins (dual function as key source).
17
GND
PWR
Connect this pin to system GND.
18,19,20,21
SEG4/KS4
to
SEG1/KS1
OUT
Segment output pins (dual function as key source).
22
KEY2
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).
23
KEY1
IN
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.
9/33
STLED316S functional description
3
STLED316S
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
VCC.
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
STLED316S
3.4
STLED316S functional description
Display types
Table 3.
3.5
Seven segment display with dot point and common-anode LED panel
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.
11/33
STLED316S functional description
3.8
STLED316S
LED drivers
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 RSET is the minimum allowed value, since it sets the display
driver to the maximum allowed segment current. RSET 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 VIL and VIH 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
4
Maximum rating
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.
Absolute maximum ratings (all voltages are referenced to GND)
Symbol
VCC
VI
Parameters
Values
Unit
-0.5 to +7.0
V
-0.5 to VCC+0.5
V
1200
mW
-40 to 85
°C
Supply voltage to ground
Logic input voltage
(1)
PD
Power dissipation
TA
Operating ambient temperature
TJ
Junction temperature
150
°C
TSTG
Storage temperature
-65 to +150
°C
300
°C
-4 to +4
kV
TL
VESD
Lead temperature (10 sec)
Electrostatic discharge voltage on all
Human body model
pins (2)
1. De-rate at -9.6 mW/°C at TA = 25°C or higher
2. In accordance with the JEDEC standard
4.1
Thermal data
Table 5.
Symbol
TthJC
Thermal data
Parameter
Thermal resistance junction-ambient
Min
Typ
75
Max
Unit
°C/W
13/33
Recommended operating conditions
STLED316S
5
Recommended operating conditions
5.1
DC electrical characteristics
Table 6.
Symbol
DC electrical characteristics
(TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0 V)
Parameter
Min
Typ
Max
Unit
4.5
5.0
5.5
V
VCC
V
VCC
Logic supply voltage
VIH
High level input voltage
High level guaranteed
digital pins
0.57
VCC
VIL
Low level input voltage
Low level guaranteed
digital pins
0
VIN = VCC or GND
-2
IIH, IIL
Input current
VHYS
Hysteresis voltage
(DIN, CLK, STB pins)
VOL(DOUT) Low level output voltage
0.3V
V
CC
0.9
1.05
DOUT, IOL2 = 4 mA
2
µA
1.2
V
0.4
V
-140
µA
Driver leakage current
Drivers off
ISEG
Segment drive LED sink current
VLED = 2.5 V
VDIGIT = VCC – 1.0
-30
-40
-50
mA
IDIG
Digit drive LED source current
VDIGIT = VCC – 1.0
240
320
400
mA
Segment drive current matching
VCC = 5.0 V, TA = 25 °C
VLED = 2.5 V
IOLEAK
ITOLSEG
RSET
14/33
Test conditions
External current setting reference
resistor
ISEG = 40 mA
(precision = ±1% tolerance)
3
%
360
Ω
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 RSET 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 = Vdiode x Idiode / VCC x ICC
As an example, consider LED with forward voltage of VF = 2.4V, Ipeak = 40 mA,
VCC (max) = 5.5 V, N = number of segments = 8 (max), D = duty cycle = 15/16,
Power dissipation, PD (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
CIN
5.4
Capacitance (TA = 25 °C, f = 1 MHz)
Parameter
Test conditions
Min
Typ
Max
Unit
15
pF
Typ.
Max.
Unit
50
1000
µA
10
15
mA
Input capacitance
Power supply characteristics
Table 8.
Symbol
ISTBY
ICC
Power supply characteristics (TA = -40 to +85 °C)
Parameter
Test conditions
Quiescent power supply VCC = 5.5 V,
current
All inputs = VCC or GND
Operating power supply
current
(display ON)
All segments ON, all digits
scanned, intensity set to full,
internal oscillator, no display
load connected
Min.
15/33
Recommended operating conditions
5.5
STLED316S
Dynamic switching characteristics
Table 9.
Symbol
Dynamic switching characteristics
(TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0.0 V, typical values are at
25 °C)
Parameter
Test conditions
fOSC
Internal oscillation frequency
fMAX
Clock (CLK) frequency
Duty = 50%
tPLZ
Propagation delay
CLK to DOUT
RL = 10 KΩ, CL = 15 pF
Min.
Typ.
Max.
Unit
400
500
600
kHz
1
MHz
tPZL
5.6
Symbol
100
ns
Timing characteristics
(TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0.0 V, Typical values are at
25 °C)
Parameter
Test conditions
Min.
Typ.
Max.
Unit
PWCLK
Clock pulse width
400
ns
PWSTB
Strobe pulse width
1
µs
tSETUP
Data setup time
100
ns
tHOLD
Data hold time
100
ns
CLK rising edge to STB
rising edge
1
µs
Test conditions
Min.
tCLK-STB Clock-strobe time
ESD performance
Table 11.
Symbol
ESD
16/33
ns
Timing characteristics
Table 10.
5.7
300
ESD performance
Parameter
JEDEC standard (all pins)
HBM
Typ.
±4
Max.
Unit
kV
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 (3rd cycle to 8th 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
STLED316S
Key matrix and key-input data storage ram
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
The data of each key are stored as illustrated below, and are read by the appropriate read
command, starting from the least significant bit.
1st byte
KEY1
KEY1
KEY1
KEY1
KEY1
KEY1
KEY1
KEY1
SEG1/KS1
SEG2/KS2
SEG3/KS3
SEG4/KS4
SEG5/KS5
SEG6/KS6
SEG7/KS7
SEG8/KS8
LSB
MSB
2nd byte
KEY2
KEY2
KEY2
KEY2
KEY2
KEY2
KEY2
KEY2
SEG1/KS1
SEG2/KS2
SEG3/KS3
SEG4/KS4
SEG5/KS5
SEG6/KS6
SEG7/KS7
SEG8/KS8
LSB
MSB
The initial key buffer value is “00”. During operation, the buffer values will change depending
upon the values of the key-press.
18/33
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).
8.1
Write command
MSB 8
Description:
MSB 7
MSB6
MSB5
LSB4
LSB3
LSB2
LSB1
LSB 3 -1 →address of the memory
MSB5 and LSB4 →address of memory bank (page)
MSB →6 ‘0’ auto increment address
‘1’ fixed address
MSB 7 →‘0’ Write command
‘1’ Read command
MSB 8 →‘X’ Unused
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
MSB 7
x
0
MSB6
X
MSB5
LSB4
LSB3
LSB2
LSB1
0
1
1
0
1
MSB5
LSB4
LSB3
LSB2
LSB1
0
1
1
1
0
Display off:
MSB 8
MSB 7
x
0
MSB6
X
Use these two commands to turn the display ‘ON’ and ‘OFF’.
19/33
Commands
8.2
STLED316S
Read command
MSB 8
Description:
MSB 7
MSB6
MSB5
LSB4
LSB3
LSB2
LSB1
LSB 3 -1 →address of the memory
MSB5 and LSB4 →address of the memory bank (page)
MSB 6 →‘0’ auto increment address
‘1’ fixed address
MSB 7 →‘0’ Write command
‘1’ Read command
MSB 8 →‘X’ Unused
Use the page 0x01 to read the LED data and key data.
Table 12.
Read command
Address
Function
00
LED data (optional)
01
Key data byte1
02
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 8th 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).
8.3
Device configuration
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
20/33
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.
Description:
Memory page mapping
Memory page
Address
Value
10
00
0xFB
10
01
0x00
10
02
0x00
10
03
0x00
11
00
0x00
11
01
0x00
11
02
0x00
11
03
0x00
Address 0x00; page 0x10
LSB 0 – 2 →indicates the number of digits in the display
LSB3 MSB 4 →'11' is for constant brightness control for the display
→'00' is for variable brightness control for the display
→'01' is reserved
→'10' is reserved
MSB 5 – 7 →indicates constant brightness control value for all including the LED
(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
MSB
LSB
0x01
Digit 2
Digit 1
0x02
Digit 4
Digit 3
0x03
Digit 6
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)
21/33
Commands
STLED316S
Table 15.
LED address mapping
Address
MSB
LSB
0x00
LED/ Seg 2
LED/ Seg 1
0x01
LED/ Seg 4
LED/ Seg 3
0x02
LED/ Seg 6
LED/ Seg 5
0x03
LED/ Seg 8
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.
8.3.1
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.
8.3.2
Dimming setting (brightness levels):
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).
22/33
STLED316S
8.4
Commands
Display memory
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
Page 2
7 segment memory
LED Display
Addr 0x00 to 0x05
(40 bit)
Addr 0x00
(8 bit)
Page 3
Page 4
7 segment brightness
LED brightness setting
setting
Addr 0x00 to 0x03
(32bit)
Addr 0x00 to 0x03
(32bit)
7-segment display memory page 0x00:
Table 17.
7-segment display address
Address
Data
0x00
0x00
0x01
0x00
0x02
0x00
0x03
0x00
0x04
0x00
0x05
0x00
LED display memory page 0x01:
Table 18.
LED display address
Address
Data
0x00h
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).
23/33
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
Seg4
Seg8
00 HL
00 HU
DIG2
01 HL
01 HU
DIG3
02 HL
02 HU
DIG4
03 HL
03 HU
DIG5
04 HL
04 HU
DIG6
05 HL
05 HU
DIG7
b0
b3
XX HL
b4
b7
XX HU
“0” in memory means GND on output; “1” in memory means VCC on output.
24/33
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 3rd-8th 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 2nd cycle is valid. Otherwise the 7-segment moves from 2nd-7th 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.
25/33
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
D IN
CLK
b0
b1
b2
2
b6
b7
3
CS15561
26/33
STLED316S
9.2
Key-scanning and display timing
Serial communication format (transmission)
The figure below shows the “transmission” from STLED316S for data read sequence.
Figure 6.
Serial communication format (transmission)
If data are contiguous
STB
D IN
CLK
b0
b1
b2
2
b6
b7
3
CS15561
Because the DIN/DOUT pin in a bi-directional pin, it is recommended to connect an external
pull-up resistor to this pin (1 KΩ to 10 KΩ).
Note:
No minimum wait time is needed to read the data from the device. The STLED316S will
output the data about 250 ns after the 8th 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 8th 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.
27/33
Switching characteristics waveform
10
STLED316S
Switching characteristics waveform
Figure 7.
Switching characteristics waveform
PWSTB
STB
PWCLK
tCLK-STB
PWCLK
CLK
tSETUP
tHOLD
DIN
tPZL
tPLZ
DOUT
tTHZ
Sn/Gn
tTZH
90%
10%
CS15562
28/33
STLED316S
Application information
11
Application information
11.1
Graph of ISET against RSET
Figure 8.
Graph of ISET against RSET
RSET
29/33
Application information
11.2
STLED316S
Power supply sequencing
Proper power-supply sequencing is advised for all CMOS devices. It is
recommended to always apply VCC before applying any signals to the input/output
or control pins.
11.3
Application diagram
Figure 9.
STLED316S application diagram
VCC
C1
C2
R2
R1
GND
VCC
6
DIG2-DIG7
CLK
LED 6-digit 7-segment (+dot-point) display panel
DIG1_LED
STB
MCU
STLED316S
DIN / DOUT
IRQ_N
SEG1/KS1
-SEG8/KS8
ISET
D1
RSET
D2
D3
D4
D5
D6
D7
D8
KEY1-KEY2
GND
R3
Keyscan
(8 x 2 matrix)
R4
GND
CS00018
Table 19.
Part list
Resistors
Capacitors
Diodes
Supply V
RSET = external
resistor for current
setting
C1 = 33 µF (25V)
electrolytic
D1-D8 = 1N4148
VCC = 5 V ± 10%
R1 = 1-10 KΩ
DIN/DOUT external
pull-up resistor
C2 = 0.01- 0.1 µF
(25 V) ceramic
R2 = 1-10 KΩ IRQ_N
external pull-up resistor
R3-R4 = 10 KΩ external
key-matrix pull-down
resistors
30/33
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
Table 20.
SO-24 package mechanical data
millimeters
inches
Symbol
Min
Typ
Max
Min
Typ
Max
A
2.35
2.65
0.093
0.104
A1
0.1
0.30
0.004
0.012
B
0.33
0.51
0.013
0.020
C
0.23
0.32
0.009
0.013
D
15.20
15.60
0.598
0.614
E
7.4
7.6
0.291
0.299
e
1.27
0.050
H
10.00
10.65
0.394
0.419
h
0.25
0.75
0.010
0.030
L
0.4
1.27
0.016
0.050
k
0°
8°
0°
8°
ddd
0.100
0.004
31/33
Revision history
13
STLED316S
Revision history
Table 21.
32/33
Document revision history
Date
Revision
9-Jan-2008
1
Changes
Initial release.
STLED316S
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33/33