LODData

0

LSB

OUT2

OUT1

OUT0

LOD

LOD

LOD

15

MSB

LOD

OUT15

OUT14

OUT13

LOD

LOD

TLC5923

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SLVS550B – DECEMBER 2004 – REVISED JANUARY 2013

Error Information Output

The open-drain output XERR is used to report both of the TLC5923 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

and XERR is pulled to GND. Since XERR is an open-drain output, multiple ICs can be OR'ed together and pulled

To differentiate LOD and TEF signal from XERR pin, LOD can be masked out with BLANK = HIGH.

Table 3. XERR Truth Table

CONDITION

ERROR INFORMATION

XERR

TEMPERATURE

BLANK

OUTn VOLTAGE

TEF

LODn

H

Don't Care

L

L

H

L

L

L

L

High-Z

H

L

H

L

L

H

L

(1)

Note: High-Z indicates high impedance

TEF: Thermal Error Flag

The TLC5923 provides a temperature error flag (TEF) circuit to indicate an overtemperature condition of the IC. If

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 TLC5923 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 10 shows the LOD data format.

Table 4 shows the LOD truth table.

Figure 10. LOD Data Format

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