TLC5955 Datasheet, PDF (27/53 Pages) Texas Instruments – TLC5955 48-Channel, 16-Bit, PWM LED Driver with DC, BC, LED Open-Short Detection, and Internal Current Setting

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TLC5955
SBVS237 – MARCH 2014
GSCLK
1 2345
31 32 33 34 35
65533 65535
65534 65536
1 2345
OUTXn current
(When GSDATA=FFFFh)
48-bit LOD/LSD
Circuit Output Data
(Internal)
96 Bit LOD/LSD
Data Latch
(Internal)
LAT
769-bit common
Shift Register Data
(Internal)
0mA (OFF)
LOD data is always 0
when OUTXn is off.
0000h
Old data
Programmed output current
(ON)
LOD/LSD data
aren’t stable just
after OUTXn on.
XXXXh
XXXXh
0mA (OFF)
Output current set by MC/DC/BC data
XXXXh
0000h
XXXXh
LOD/LSD data latch is updated at 33rd GSCLK of the display period.
XXXXh
XXXXh
LAT signal for
grayscale data writing
Grayscale Data
When RFRESH bit is 1, SID is loaded
at 65536th GSCLK and SCLK must be
input after 1st GSCLK input.
XXXXh is loaded as SID.
Figure 26. LOD and LSD Read and Load Timing Diagram
8.3.6 Noise Reduction
Large surge currents may flow through the device and the board on which the device is mounted if all 48 outputs
turn on simultaneously at the start of each GS cycle. These large current surges can introduce detrimental noise
and electromagnetic interference (EMI) into other circuits. The TLC5955 independently turns the outputs on with
a series delay for each group to provide a soft-start feature. The output current sinks are grouped into eight
groups. The first output group that is turned on or off are OUTR4, OUTG4, OUTB4, OUTR11, OUTG11, and
OUTB11; the second output group is OUTX0 and OUTX15; the third output group is OUTX5 and OUTX10; the
fourth output group is OUTX1 and OUTX14; the fifth output group is OUTX2 and OUTX13; the sixth output group
is OUTX6 and OUTX9; the seventh output group is OUTX3 and OUTX12; and the eighth output group is OUTX7
and OUTX8. Each output group is turned on and off sequentially with a small delay between groups.
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