TLC5905 Datasheet, PDF (13/27 Pages) Texas Instruments – LED DRIVER

TLC5905
LED DRIVER
PRINCIPLES OF OPERATION
SLLS401 – NOVEMBER 1999
shift register latch for gray scale data
The shift register latch for gray scale data is set as a 64 x 1 bit configuration in the 8-bit mode, and as a 128
x 1 bit configuration in the 16-bit mode. The gray scale data, configured as 8 bits, represents the time when
constant current output is being turned on, and the data range is 0 to 255 (00h to FFh). When the gray scale
data is 0, the time is shortest, and the output is not turned on(light off). On the other hand, when the gray scale
data is 255, the time is longest, and it turns on during time of 255 clocks from GSCLK. The configuration of shift
register and latch for gray scale data is shown in Figure 3.
XLATCH
Latch for Gray Scale Data
OUT15 Data
(8 bits)
OUT14 Data
(8 bits)
..........
OUT1 Data
(8 bits)
OUT0 Data
(8 bits)
Shift Register for Gray Scale Data
SOUT
MSB
128
121 120
..........
113
16
9
8
LSB
0
XLATCH
16 Bit Mode (MODE=H, RSEL0 and RSEL1=L)
Latch for Gray Scale Data
OUT15,14 Data
(8 bits)
OUT13,12 Data
(8 bits)
..........
OUT3,2 Data
(8 bits)
OUT1,0 Data
(8 bits)
SCLK
SIN
Shift Register for Gray Scale Data
SOUT
MSB
64
57 56
..........
49
16
9
8
LSB
0
8 Bit Mode (MODE=L, RSEL0 and RSEL1=L)
Figure 3. Relationship Between Shift Register and Latch for Gray Scale Data
SCLK
SIN
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