TLC5973 Datasheet, PDF (19/34 Pages) Texas Instruments – TLC5973 3-Channel, 12-Bit, PWM Constant-Current LED Driver with Single-Wire Interface (EasySet)

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TLC5973
SBVS225B – MARCH 2013 – REVISED MAY 2014
8.5 Programming
8.5.1 Controlling Devices Connected in Series
The 12-bit write command and 36-bit grayscale (GS) data for OUT0 to OUT2 (for a total of 48 bits of data) must
be written to the device. Figure 18 shows the 48-bit data packet configuration. When multiple devices are
cascaded (as shown in Figure 19), N times the packet must be written into each TLC5973 in order to control all
devices. There is no limit on how many devices can be cascaded, as long as proper VCC voltage is supplied.
The packet for all devices must be written again whenever any GS data changes.
MSB
Data 0 Data 0
for t_CYCLE for t_CYCLE
Data
1
Data
1
Data
1
Data
0
Data
1010
Data
1
Data
0
Data
0 or 1
Data
0 or 1
Data
0 or 1
Data
0 or 1
Data
0 or 1
LSB
Data
0 or 1
Bit 11
Write Command Data, 12 Bits
(3AAh = 001110101010b)
Bit 0
Bit 11 _OUT0
Bit 0
GS Data, 12 Bits
Bit 11 _OUT1
Bit 0
GS Data, 12 Bits
Bit 11 _OUT2 Bit 0
GS Data, 12 Bits
Figure 18. 48-Bit Data Packet Configuration for One TLC5973
V_LED
5.0 V
R_VCC
VCC
Controller
CLK
GND
C_VCC
0.1 µF
GND
R_VCC
1st Device
VCC
SDI
SDO
IREF
GND
GND
R_VCC
2nd Device
VCC
SDI
SDO
IREF
GND
GND
R_VCC
N-1st Device
VCC
SDI
SDO
IREF
GND
GND
Nth Device
VCC
SDI
SDO
IREF
GND
GND
Figure 19. Cascade Connection of N TLC5973 Units (Internal Shunt Regulator Mode)
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