TLC5973 Datasheet, PDF (20/34 Pages) Texas Instruments – TLC5973 3-Channel, 12-Bit, PWM Constant-Current LED Driver with Single-Wire Interface (EasySet)

TLC5973
SBVS225B – MARCH 2013 – REVISED MAY 2014
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Programming (continued)
The function setting write procedure and display control is:
1. Power-up VCC (V_LED); all OUTn are off because GS data are not written yet.
2. Write the 48-bit data packet (MSB-first) for the first device using t_CYCLE and the data write sequences
illustrated in Figure 14 and Figure 15. The first 12 bits of the 48-bit data packet are used as the write
command. The write command must be 3AAh (001110101010b); otherwise, the 36-bit GS data in the 48-bit
shift register are not copied to the 36-bit GS data latch.
3. Execute one communication cycle EOS (refer to Figure 16) for the first device.
4. Write the 48-bit data packet for the second TLC5973 as described step 2. However, t_CYCLE should be set to
the same timing as the first device.
5. Execute one communication cycle EOS for the second device.
6. Repeat steps 4 and 5 until all devices have GS data.
7. The number of total bits is 48 × N. After all data are written, execute a GSLAT sequence as described in
Figure 17 in order to copy the 36-bit LSBs in the 48-bit shift resister to the 36-bit GS data latch in each
device; PWM control starts with the written GS data at the same time.
V_LED Power
1st Device SDI
MSB
LSB
MSB
LSB
MSB
48-Bit Data Packet
for 1st Device
EOS
48-Bit Data Packet
for 2nd Device
EOS ^{For 3rd}
Device
LSB
MSB
LSB
For
N-1th
EOS
48-Bit Data Packet
for Nth Device
GSLAT
MSB
LSB
Next Data Packet
for 1st Device
1st Device SDO
48-Bit Data Packet
for 2nd Device
For 3rd
EOS _Device
For
48-Bit Data Packet
N-1th ^EOS for Nth Device
GSLAT
N-2nd Device SDO
N-1st Device SDO
OUTn
For 3rd
Device
For
N-1st
EOS ^{48-Bit Data Packet}
for Nth Device
GSLAT
48-Bit Data Packet _GSLAT
for Nth Device
Figure 20. Data Packet Input Order for N TLC5973 Units
PWM Control Starts
with new GS Data
20
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