- Device state: ACTIVE
- Mechanism & thresholds: An analog current limit circuit on each MOSFET limits the peak current out of the device even in hard short circuit events. If the output current exceeds the overcurrent threshold, IOCP, for longer than tOCP, then an over current fault is detected.
- Action:
- nFAULT pin is asserted low
- Reaction is based on mode selection:
- PH/EN or PWM mode - Both OUTx is Hi-Z
- Independent mode - the affected half-bridge OUTx is Hi-Z
- For a short to GND fault (over current detected on the high-side FET), the IPROPI pin continues to be pulled up to VIPROPI_LIM even if the FET has been disabled. For the HW variant, this helps differentiate a short to GND fault during ACTIVE state from other fault types, as the IPROPI pin is pulled high while the nFAULT pin is asserted low.
- Reaction configurable between latch setting and retry setting based on tRETRY and tCLEAR
- User can add a capacitor in the range of 10nF to
100nF on the IPROPI pin to maintain OCP detection in case of a load short
condition when internal ITRIP regulation is enabled. This is especially true
where there is enough inductance in the short that causes ITRIP regulation
to trigger ahead of the OCP detection, resulting in the device missing the
short detection. To maintain that OCP detection wins this race condition, a
small capacitance added on the IPROPI pin slows down the ITRIP regulation
loop enough to allow the OCP detection circuit to work as intended.
The SPI variant offers configurable IOCP levels and tOCP filter times. Refer CONFIG4 register for these settings.