TLC5947_17 Datasheet, PDF (16/33 Pages) Texas Instruments – 24-Channel, 12-Bit PWM LED Driver With Internal Oscillator

TLC5947
SBVS114B – JULY 2008 – REVISED JANUARY 2015
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Programming (continued)
GS DATA
(Binary)
0000 0000 0000
0000 0000 0001
0000 0000 0010
0000 0000 0011
—
0111 1111 1111
1000 0000 0000
1000 0000 0001
—
1111 1111 1101
1111 1111 1110
1111 1111 1111
Table 1. GS Data versus On Duty
GS DATA
(Decimal)
0
1
2
3
—
2047
2048
2049
—
4093
4094
4095
GS DATA
(Hex)
000
001
002
003
—
7FF
800
801
—
FFD
FFE
FFF
DUTY OF DRIVER TURN-ON
TIME (%)
0.00
0.02
0.05
0.07
—
49.98
50.00
50.02
—
99.93
99.95
99.98
GS data are transferred from the shift register to the latch by the rising edge of XLAT. When powered up, the
data in the grayscale shift register and data latch are not set to default values. Therefore, grayscale data must be
written to the GS latch before turning on the constant-current output. BLANK should be at a high level when
powered on to avoid falsely turning on the constant-current outputs due to random values in the latch at power-
up. All of the constant-current outputs are forced off when BLANK is high. However, if the random values turning
on at power-up is not a concern in the application, BLANK can be at any level. GS can be controlled correctly
with the grayscale data writing functions, even if BLANK is connected to GND. Equation 1 determines each
output on duty.
On Duty (%) =
GSn
4096
´ 100
where
• GSn = the programmed grayscale value for OUTn (GSn = 0 to 4095)
(1)
16
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