TLC5924_16 Datasheet, PDF (12/28 Pages) Texas Instruments – 16-CHANNEL LED DRIVER WITH DOT CORRECTION AND PRE-CHARGE FET

TLC5924
SLVS626 – JUNE 2006
www.ti.com
Error Information Output
The open-drain output XERR is used to report both of the TLC5924 error flags, TEF and LOD. During normal
operating conditions, the internal transistor connected to the XERR pin is turned off. The voltage on XERR is
pulled up to V_CC through a external pull-up resistor. If TEF or LOD is detected, the internal transistor is turned
on, and XERR is pulled to GND. Since XERR is an open-drain output, multiple ICs can be OR'ed together and
pulled up to V_CC with a single pull-up resistor. This reduces the number of signals needed to report a system
error.
To differentiate LOD and TEF signal from XERR pin, LOD can be masked out with BLANK = HIGH.
Table 3. XERR Truth Table
TEMPERATURE
T_J < T_(TEF)
T_J > T_(TEF)
T_J < T_(TEF)
T_J > T_(TEF)
CONDITION
BLANK
H
L
OUTn VOLTAGE
Don't Care
OUTn > V_(LOD)
OUTn < V_(LOD)
OUTn > V_(LOD)
OUTn < V_(LOD)
(1) Note: High-Z means high impedance
ERROR INFORMATION
TEF
LODn
L
L
H
L
L
H
H
L
H
XERR
High-Z ⁽¹⁾
L
High-Z
L
L
L
TEF: Thermal Error Flag
The TLC5924 provides a temperature error flag (TEF) circuit to indicate an over-temperature condition of the IC.
If the junction temperature exceeds the threshold temperature T_(TEF) (160°C typical), TEF becomes H and XERR
pin goes to low level. When the junction temperature becomes lower than the threshold temperature, TEF
becomes L and XERR pin becomes high impedance.
LOD: LED-Open Detection
The TLC5924 has an LED-open detector to detect broken or disconnected LEDs, which should be connected to
the output. The LED-open detector pulls the XERR pin down to GND when the LED open is detected. An open
LED is detected when the following three conditions are met:
1. BLANK is low
2. On/Off data is high
3. The voltage of OUTn is less than 0.3 V (typical)
The LOD status of each output can also be read out from the SOUT pin. Figure 12 shows the LOD data format.
Table 4 shows the LOD truth table.
MSB
15
LOD
OUT15
LOD
OUT14
LOD
OUT13
LOD LOD
OUT2 OUT1
LOD Data
Figure 12. LOD Data Format
LSB
0
LOD
OUT0
12
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