TLC5954 Datasheet, PDF (21/45 Pages) Texas Instruments – TLC5954 48-Channel, Constant-Current LED Driver with Global Brightness Control, LED Open-Short Detection, and Power-Save Mode

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TLC5954
SBVS241 – APRIL 2014
SIDLD in FC
Data Latch
(Internal)
BLANK
OUTXn Current
for LED Lighting
48-Bit LOD
Circuit Output Data
(Internal)
SID Holder Data
(Internal)
LAT
01b
H
0mA
LOD = 0000h
Old data
L
2 mA to 34.9 mA (for OUTRn, OUTGn),
1.4 mA to 24.4 mA (for OUTBn)
when BC data are maximum.
48-bit LOD data are not stable for
1 µs after BLANK goes low.
LOD = XXXXh
LOD data go through the SID holder
when BLANK is low.
LOD = XXXXh
0 mA
LOD = 0000h
48-bit data are held in the
SID holder when BLANK is high.
48-Bit Output
On or Off Data Latch
(Internal)
48-Bit Common
Shift Register
(Internal)
Old output on or off data.
New output on or off data.
Latched in output on or off data.
Figure 30. LOD Operation Timing Diagram
LOD data (XXXXh) are loaded
into the shift register.
8.3.4 LED Short Detection (LSD)
LSD data detect a fault caused by a shorted LED by comparing the OUTXn voltage to the LSD detection
threshold voltage level set by LSDVLT in the function control data latch (see Table 6 and Table 9). If the OUTXn
voltage is higher than the programmed voltage, the corresponding output LSD bit is set to 1 to indicate a shorted
LED. Otherwise, the LSD bit is set to 0. LSD data are only valid for outputs that are set to 1 in the output on-off
data latch. LSD data are always 0 for outputs that are set to 0 in the output on-off data latch.
LSD data are loaded into a 48-bit register called the SID holder at the BLANK rising edge when the SIDLD bits
are set to 10b (see Table 7). The loaded LSD data can be read out through the common shift register as SID
data at the SOUT pin. LSD data are not valid for 1 μs after the output is turned on. If the OUTXn controlled by
the BLANK pin is less than 1 µs, the LSD data must be ignored.
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