TLC59291_16 Datasheet, PDF (29/46 Pages) Texas Instruments – 8/16-Channel, Constant Current LED Driver

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TLC59291
SLVSA96A – SEPTEMBER 2015 – REVISED MARCH 2016
Device Functional Modes (continued)
8.4.5 Invisible Detection Mode (IDM)
Invisible Detection Mode (IDM) is the mode which can detect LOD and LSD when output on-off data is set to off
state. When “IDMCUR” bit in the control data latch are set any data except “00b”, OUTn start to sink the current
set by the “IDMCUR” bit at BLANK falling edge and OUTn stop to sink the current at BLANK rising signal or the
time set by “IDMTIM” has passed. When OUTn is stopped, the selected SID data by “SIDLD” bit are latched to
into SID holder.
When IDM mode is enabled, OLD is always set to disable. When “IDMCUR” bit in the control data latch is set
“00b”, OUTn doesn’t start to sink the current set. Figure 29 shows LOD/LSD/OLD/IDM circuit. Figure 8 shows
IDM operation timing and Table 5 shows a truth table for LOD/LSD/OLD.
IDM can only be working when FC[9] = 1.
8.4.6 Output Leakage Detection (OLD)
Output leak detection (OLD) detects a fault caused by OUTn is short to GND with high resistance by comparing
the OUTn voltage to the LSD detection threshold voltage when output on-off data is set to off state. Also OLD
can detect the short between adjacent pins. Small current is sourced from OUTn turned off to LED to detect LED
leaking when “SIDLD” bit are ‘11b’ and BLANK is low. OLD operation is disabled when SIDLD bit are set any
data except “11b” and then the sourced current is stopped. Also OLD is disabled when Invisible Detection Mode
(IDM) is enabled. If the OUTn voltage is lower than the programmed LSD threshold voltage, that output OLD bit
is set to '1' to indicate a leaking LED. Otherwise, the OLD bit is set to '0'. OLD result is valid for outputs
programmed to off only. The OLD data is latched into SID holder when BLANK goes high. OLD data for outputs
not programmed to off are always '0'. The OLD need to be executed after propagation delay, “td4” or more from
the device operation resumed from the power save mode because OLD does not work during the power save
mode.
VCC
VLED
OLD
Control
2 mA (typ)
LED Lamp
LSD/OLD Data
‘1’ = Error
LOD Data
‘1’ = Error
V_LSD
On/Off
Control
Up to
50 mA
IDM
Control
OUTn
2 mA/10 mA/20 mA
(typ)
V_LOD
GND
Figure 29. LOD/LSD/OLD/IDM Circuit
8.4.7 Status Information Data (SID)
The status information data (SID) contains the status of the LED Open Detection (LOD), LED Short Detection
(LSD), Output Leakage Detection (OLD), Pre-Thermal Warning (PTW), Thermal Shutdown (TSD) and Thermal
Error Flag (TEF) and Current Reference Terminal – IREF Terminal - Short Flag (ISF). The loaded SID data can
be selected by “SIDLD” bits in the control data latch. When the MSB of the common shift register is set to '0', the
selected SID overwrites lower 16-bit data in the common shift register data at the rising edge of LAT after the
data in the common shift register are copied to the output on-off data latch. If the common shift register MSB is
'1', the selected SID does not overwrite the 16-bit data in the common shift register
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