TLC5946 Datasheet, PDF (19/35 Pages) Texas Instruments – 16-Channel, 12-Bit PWM LED Driver with 6-Bit Dot Correction

TLC5946
www.ti.com ......................................................................................................................................................... SLVS824A – MARCH 2008 – REVISED APRIL 2008
AUTO OUTPUT OFF
The V_CC current (ICC) increases during an LED open detection. When the TLC5946 detects an open or shorted
to ground LED at OUTn, the TLC5946 turns off OUTn to reduce the ICC at the 33rd falling edge of GSCLK after
the falling edge of BLANK, as shown in Figure 28. This feature minimizes supply current during fault conditions.
If there are any unconnected output LED lamps (including connection failures or short-circuits), the grayscale
data corresponding to the unconnected output should be set to '0' before turning on the LEDs.
BLANK
GSCLK
OUTn Voltage
(GS Data = FFFd)
LOD Data Latch
(Internal)
123
31 32 33 34 35
4096
V_OUTn < V_LOD
0 (Previous Data)
Auto Output Off
1 (Updated Data)
123
31 32 33 34 35
4096
XERR
ICC
Figure 28. LOD and Auto Output Off Timing
THERMAL ERROR FLAG (TEF)
The TLC5946 has a thermal error flag (TEF) function to indicate an over-temperature condition. If the junction
temperature exceeds the threshold temperature, +162°C typical, TEF toggles to '1' and the XERR pin goes to a
low level. Once TEF becomes '1', it remains a '1' until the first falling edge of SCLK after XLAT goes low, as
shown in Figure 29. If the junction temperature (T_J) remains higher than the threshold temperature, TEF remains
'1', even after the first falling edge of SCLK. TEF is also shifted out of the SOUT pin; see the Status Information
Data (SID) section.
XLAT
BLANK
SCLK
GSCLK
1234
123
IC Junction
Temperature (T_J)
TEF
(Internal)
XERR
T_J < T_TEF
'0'
Hi-Z
T_J ³ T_TEF
'1'
T_J < T_TEF - T_HYS
Low
Figure 29. TEF and XERR Timing
T_J ³ T_TEF
'0'
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