The TPS92624-Q1 device has LED open-circuit detection. The LED open-circuit detection monitors the output voltage when the current output is enabled. The LED open-circuit detection is only enabled when DIAGEN is HIGH. A short-to-battery fault is also detected and recognized as an LED open-circuit fault.

The TPS92624-Q1 monitors dropout-voltage differences between the IN and OUT pins for each LED channel when PWM is HIGH. The voltage difference V_(INx) – V_(OUTx) is compared with the internal reference voltage V_{(OPEN_th_rising)} to detect an LED open-circuit incident. If V_(OUTx) rises and causes V_(INx) – V_(OUTx) less than the V_{(OPEN_th_rising)} voltage longer than the deglitch time of t_{(OPEN_deg)}, the device asserts an open-circuit fault. After a LED open-circuit failure is detected, the internal constant-current sink pulls down the FAULT pin voltage. During the deglitch time period, if V_(OUTx) falls and makes V_(INx) – V_(OUTx) larger than V_{(OPEN_th_falling)}, the deglitch timer is reset.

The TPS92624-Q1 shuts down the output current regulation for the error channel after LED open-circuit fault is detected. The device sources a small current I_(Retry) from SUPPLY to OUT and RES when DIAGEN input is logic High. After the fault condition is removed, the device resumes normal operation and releases the FAULT pin. Figure 7-4 illustrates the timing for LED open-circuit detection, protection, retry and recovery.

The detailed information and value of each time period in Figure 7-4 is described in Timing Requirements.