TLC5941 Datasheet, PDF (14/23 Pages) Texas Instruments – 16-CHANNEL LED DRIVER WITH DOT CORRECTION AND GRAYSCALE PWM CONTROL

TLC5941
SLVS589 – JULY 2005
www.ti.com
LSB
0
5
6
DC 0.0
DC 0.5 DC 1.0
DC OUT0
DC OUT2 − DC OUT14
79
90
MSB
95
DC 14.5 DC 15.0
DC 15.5
DC OUT15
Figure 7. Dot Correction Data Packet Format
To input data into the dot correction register, MODE must be set to V_CC. The internal input shift register is then
set to 96-bit width. After all serial data are clocked in, a rising edge of XLAT is used to latch the data into the dot
correction register. Figure 8 shows the dc data input timing chart.
DC Mode Data
Input Cycle n
V_CC
DC Mode Data
Input Cycle n+1
MODE
SIN
DC n−1
LSB
DC n
MSB
DC n
MSB−1
DC n
MSB−2
DC n
LSB+1
DC n
LSB
DC n+1
MSB
DC n+1
MSB−1
SCLK
SOUT
t_wh0
1
2
3
DC n−1
MSB
DC n−1
MSB−1
t_wl0
DC n−1
MSB−2
XLAT
95
96
DC n−1 DC n−1
LSB+1
LSB
t_su1
DC n
MSB
t_wh2
t_h1
1
2
DC n
DC n
MSB−1 MSB−2
Figure 8. Dot Correction Data Input Timing Chart
SETTING GRAYSCALE
The TLC5941 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, from 0% to 100% brightness. Equation 4 determines the
brightness level for each output n:
Brightness
in
%
+
GSn
4095
100
(4)
where:
GSn = the programmed grayscale value for output n (GSn = 0 to 4095)
n = 0 to 15
Grayscale data for all OUTn
The input shift register enters grayscale data into the grayscale register for all channels simultaneously. The
complete grayscale data format consists of 16 x 12 bit words, which forms a 192-bit wide data packet (see
Figure 9). The data packet must be clocked in with the MSB first.
14