TLC5940-EP Datasheet, PDF (19/33 Pages) Texas Instruments – 16-CHANNEL LED DRIVER WITH DOT CORRECTION AND GRAYSCALE PWM CONTROL

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VPRG
VCC
DCPRG
V(PRG)
t_su6
t_prog
TLC5940-EP
SLVSA51D – MARCH 2010 – REVISED MAY 2010
t_h5
XLAT
SIN
DC
MSB
DC
LSB
SCLK
1
96
SOUT
-
DC
MSB
Figure 17. EEPROM Programming Timing Chart
DCPRG
OUT0
(Current)
t_pd5
t_pd5
OUT15
(Current)
Figure 18. DCPRG and OUTn Timing Diagram
SETTING GRAYSCALE
The TLC5940 can adjust the brightness of each channel OUTn using a PWM control scheme. The use of 12 bits
per channel results in 4096 different brightness steps, respective 0% to 100% brightness. Equation 9 determines
the brightness level for each output n:
Brightness
in
%
+
GSn
4095
100
(9)
where:
GSn = the programmed grayscale value for output n (GSn = 0 to 4095)
n = 0 to 15
Grayscale data for all OUTn
Figure 19 shows the grayscale data packet format which consists of 12 bits x 16 channels, totaling 192 bits. The
format is Big-Endian format. This means that the MSB is transmitted first, followed by the MSB-1, etc.
MSB
191
180
179
12
11
LSB
0
GS 15.11
GS 15.0 GS 14.11
GS OUT15
GS OUT14 − GS OUT2
GS 1.0 GS 0.11
GS 0.0
GS OUT0
Figure 19. Grayscale Data Packet Format
When VPRG is set to GND, the TLC5940 enters the grayscale data input mode. The device switches the input
shift register to 192-bit width. After all data is clocked in, a rising edge of the XLAT signal latches the data into
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