TLC59401 Datasheet, PDF (16/29 Pages) Texas Instruments – 16-CHANNEL LED DRIVER WITH DOT CORRECTION AND GRAYSCALE PWM CONTROL

TLC59401
SBVS137 – DECEMBER 2009
www.ti.com
SETTING DOT CORRECTION
The TLC59401 has the capability to fine-adjust the output current of each channel (OUT0 to OUT15)
independently. This feature is also called dot correction. This feature is used to adjust the brightness deviations
of LEDs connected to the output channels OUT0 to OUT15. Each of the 16 channels can be programmed with a
6-bit word. The channel output can be adjusted in 64 steps from 0% to 100% of the maximum output current I_max.
The TEST pin must be connected to V_CC to ensure proper operation of the dot correction circuitry. Equation 8
determines the output current for each output n:
IOUTn + Imax
DCn
63
(8)
where:
I_max = the maximum programmable output current for each output.
DCn = the programmed dot correction value for output n (DCn = 0 to 63).
n = 0 to 15
Figure 15 shows the dot correction data packet format which consists of 6 bits x 16 channel, total 96 bits. The
format is Big-Endian format. In this format, the MSB is transmitted first, followed by the MSB-1, etc. The DC 15.5
in Figure 15 stands for the fifth-most significant bit for output 15.
MSB
0
5
6
DC 15.5
DC 15.0 DC 14.5
DC OUT15
DC OUT14 − DC OUT1
LSB
89
90
95
DC 1.0 DC 0.5
DC 0.0
DC OUT0
Figure 15. Dot Correction Data Packet Format
When MODE is set to V_CC, the TLC59401 enters the dot correction data input mode. The length of the input shift
register becomes 96 bits. After all serial data are shifted in, the TLC59401 writes the data in the input shift
register to the DC register when XLAT is high, and holds the data in the DC register when XLAT is low. The DC
register is a level-triggered latch of the XLAT signal. Because XLAT is a level-triggered signal, SCLK and SIN
must not be changed while XLAT is high. After XLAT goes low, data in the DC register are latched and do not
change. The BLANK signal does not need to be high to latch in new data. When XLAT goes high, the new
dot-correction data immediately become valid and change the output currents if BLANK is low. XLAT has a setup
time (t_su1) and a hold time (t_h1) to SCLK, as shown in Figure 12.
16
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