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TLC5947 Datasheet, PDF (15/25 Pages) Texas Instruments – 24-Channel, 12-Bit PWM LED Driver with
◁
TLC5947
www.ti.com....................................................................................................................................................................................................... SBVS114 – JULY 2008
REGISTER CONFIGURATION
The TLC5947 has a grayscale (GS) data shift register and data latch. Both the GS data shift register and latch
are 288 bits long and are used to set the PWM timing for the constant current driver. Table 2 shows the on duty
cycle for each GS data. Figure 19 shows the shift register and data latch configuration. The data at the SIN pin
are shifted to the LSB of the shift register at the rising edge of the SCLK pin; SOUT data are shifted out on the
falling edge of SCLK. The timing diagram for data writing is shown in Figure 20. The driver on duty is controlled
by the data in the GS data latch.
Grayscale Data Shift Register (12 Bits 24 Channels)
´
SOUT
GS Data for OUT23
MSB
287
GS Data for
Bit 11 of
OUT23
¼
276
GS Data for
Bit 0 of
OUT23
GS Data for OUT22 GS Data for OUT1
¼
GS Data for OUT0
LSB
275
12
11
0
GS Data for
Bit 11 of
OUT22
¼
GS Data for
GS Data for
Bit 11 of
Bit 0 of OUT1
OUT0
GS Data for
¼
Bit 0 of OUT0
SIN
SCLK
¼
¼
¼
GS Data for OUT23
MSB
287
GS Data for
Bit 11 of
OUT23
¼
276
GS Data for
Bit 0 of
OUT23
¼ GS Data for OUT22 GS Data for OUT1
GS Data for OUT0
LSB
275
12
11
0
GS Data for
Bit 11 of
OUT22
¼
GS Data for
GS Data for
Bit 11 of
Bit 0 of OUT1
OUT0
GS Data for
¼
Bit 0 of OUT0
XLAT
Grayscale Data Latch (12 Bits 24 Channels)
´
288 Bits
To PWM Timing Control Block
Figure 19. Grayscale Data Shift Register and Latch Configuration
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 2. 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
Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): TLC5947
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