JAJSNQ5 may 2023 TPS92629-Q1
PRODUCTION DATA
The TPS92629-Q1 device has LED open-circuit detection and output short-to-battery detection. The LED open-circuit detection and output short-to-battery detection monitor the output voltage when the current output is enabled. The LED open-circuit detection and output short-to-battery are only enabled when DIAGEN is HIGH. Compared with the traditional detection method, output short-to-battery fault and LED open-circuit fault could be identified.
The TPS92629-Q1 monitors dropout-voltage differences between the IN and OUT pins for LED channel when PWM is HIGH and ADIM 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 and output short-to-battery 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 fault immediately and pulls down the fault pin firstly. 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. After the falling edge of fault pin, there is a discharge time t(discharge) to identify whether it is output short-to-battery fault or LED open-circuit fault. During the discharge stage, I(Discharge_OUT) flows into the out pin. At the end of discharge stage, the voltage difference V(INx) – V(OUTx) is compared with the internal reference voltage V(OPEN_th_falling). When V(INx) – V(OUTx) is bigger than V(OPEN_th_falling), the LED open-circuit fault is reported. Otherwise, output short-to-battery fault is reported.
The TPS92629-Q1 shuts down the output current regulation for the error channel after LED open-circuit fault or output short-to-battery 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 7-3 illustrates the timing for LED open-circuit detection, protection, retry and recovery.
The detailed information and value of each time period in Figure 7-3 is described in TIMING section of electrical characteristics table.