TLC5942_16 Datasheet, PDF (16/29 Pages) Texas Instruments – 16-Channel, 12-Bit PWM LED Driver with 7-Bit Dot Correction

TLC5942
Not Recommended for New Designs
SBVS096B – OCTOBER 2007 – REVISED OCTOBER 2007
www.ti.com
Dot Correction (DC) Function
The TLC5942 is able to individually adjust the output current of each channel (OUT0 to OUT15). This function is
called dot correction (DC). The DC function allows users to individually adjust the brightness and color deviations
of LEDs connected to the outputs OUT0 to OUT15. Each respective channel output current can be adjusted in
128 steps from 0% to 100% of the maximum output current, I_OLCMax. The dot correction data are entered into the
TLC5942 via the serial interface.
Equation 2 determines the sink current for each output (OUTn):
I_OUTn
(mA)
=
I_OLCMax
(mA)
´
(
DCn
127d
)
(2)
Where:
I_OLCMax = the maximum channel current for each channel determined by R_IREF
DCn = the programmed dot correction value for OUTn (DCn = 0 to 127d)
When the IC is powered on, the data in the Dot Correction Shift Register and data latch are not set to any default
values. Therefore, DC data must be written to the DC latch before turning on the constant current output.
Table 2 summarizes the DC data versus current ratio and set current value.
DC DATA
(Binary)
000 0000
000 0001
000 0010
... ...
111 1101
111 1110
111 1111
Table 2. DC Data versus Current Ratio and Set Current Value
DC DATA
(Decimal)
0
1
2
... ...
125
126
127
DC DATA
(Hex)
00
01
02
... ...
7D
7E
7F
SET CURRENT
RATIO TO
MAX CURRENT (%)
0.0
0.8
1.6
... ...
98.4
99.2
100.0
OUTPUT CURRENT
(mA, typical)
AT I_OLCMax = 50 mA
0.0
0.4
0.8
... ...
49.2
49.6
50.0
OUTPUT CURRENT
(mA, typical)
AT I_OLCMax = 5 mA
0.00
0.04
0.08
... ...
4.92
4.96
5.00
16
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