TLC5926_15 Datasheet, PDF (15/39 Pages) Texas Instruments – 16-Channel Constant-Current LED Sink Drivers

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TLC5926, TLC5927
SLVS677C – JULY 2008 – REVISED OCTOBER 2015
9.4 Device Functional Modes
The TLC592x provides a Special Mode in which two functions are included, Error Detection and Current Gain
Control. In the TLC592x there are two operation modes and three phases: Normal Mode phase, Mode Switching
transition phase, and Special mode phase. The signal on the multiple-function pin OE(ED2) is monitored, and
when a one-clock-wide short pulse appears on OE(ED2), TLC592x enters the Mode Switching phase. At this
time, the voltage level on LE(ED1) determines the next mode into which the TLC592x switches.
In the Normal Mode phase, the serial data is transferred into TLC592x via SDI, shifted in the shift register, and
transferred out via SDO. LE(ED1) can latch the serial data in the shift register to the output latch. OE(ED2)
enables the output drivers to sink current.
In the Special Mode phase, the low-voltage-level signal OE(ED2) can enable output channels and detect the
status of the output current, to tell if the driving current level is enough or not. The detected error status is loaded
into the 16-bit shift register and shifted out via SDO, along with the CLK signal. The system controller can read
the error status to determine whether or not the LEDs are properly lit. In the Special Mode phase, TLC592x also
allows users to adjust the output current level by setting a runtime-programmable Configuration Code. The code
is sent into TLC592x via SDI. The positive pulse of LE(ED1) latches the code in the shift register into a built-in 8-
bit configuration latch, instead of the output latch. The code affects the voltage at R-EXT and controls the output-
current regulator. The output current can be adjusted finely by a gain ranging from 1/12 to 127/128 in 256 steps.
Therefore, the current skew between ICs can be compensated within less than 1%, and this feature is suitable
for white balancing in LED color-display panels.
CLK
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
OE(ED2) 1
LE(ED1) ₀
SDI
off
OUT0
on
off
OUT1
on
off
OUT2
on
off
OUT3
on
off
OUT15
on
SDO
Don't care
Figure 7. Normal Mode
Table 4. Truth Table in Normal Mode
CLK
↑
↑
LE(ED1)
H
L
OE(ED2)
L
L
SDI
Dn
Dn + 1
OUT0...OUT15
Dn...Dn – 7...Dn – 15
No change
SDO
Dn – 15
Dn – 14
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