TLC5971 Datasheet, PDF (29/37 Pages) Texas Instruments – 12-Channel 16-Bit, Enhanced Spectrum PWM, RGB LED Driver with 3.3-V Linear Regulator

TLC5971
www.ti.com
SBVS146 – AUGUST 2010
VLED Power
Shift Data From
Controller (SDTI)
Shift Clock From
Controller (SCKI)
Latch Pulse
(Internal)
OUTXn
MSB
LSB
224-Bit Packet for for
256th TLC5971 255th
MSB
The next shift clock should start after 1.34 ms or more from the internal latch pulse generation timing.
MSB
LSB
for
224-Bit Packet
2nd
for 1st TLC5971
LSB
Timing clock for 1st display.
Timing clock for 1st display and
2nd display data write.
Low
256 ´ 224-Bit Packet for
256th TLC5971
Low
224 Shift Clocks
224 Shift Clocks
224 ´ 256 = 57344 Clocks
8192
Shift Clocks
57344 (256 ´ 224)
Shift Clocks
65536 Clocks
Shift Clock
for 2nd Display
65536 Clocks
OFF
OUTXn is controlled via the PWM synchronized
with SCKI for 1st dis playperiod.
OFF
2nd Display
Period
The time is 8 periods between the last SCLK rising edge and the second to last SCLK rising edge.
The wait time changes between 2.74 ms and 666 ns, depending on the period of the shift clock.
Figure 35. Data Packet and Display Start/Update Timing 3
(External Clock Mode with 256 Cascaded Devices)
THERMAL SHUTDOWN
The thermal shutdown (TSD) function turns off all IC constant-current outputs when the junction temperature (T_J)
exceeds the threshold (T_TSD = +165°C, typ). When the junction temperature drops below (T_TSD – T_HYS), the
output control starts at the first GS clock in the next display period.
NOISE REDUCTION
Large surge currents may flow through the IC and the board if all 12 outputs turn on simultaneously at the start of
each GS cycle. These large current surges could induce detrimental noise and EMI into other circuits. The
TLC5971 turns on the outputs for each color group independently with a 25 ns (typ) rise time. The output current
sinks are grouped into three groups. The first group that is turned on/off are OUTR0-3; the second group that is
turned on/off are OUTG0-3; and the third group is OUTB0-3. However, the state of each output is controlled by
the selected GS clock; see the Output Timing Select Function section.
Copyright © 2010, Texas Instruments Incorporated
Product Folder Link(s): TLC5971
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