- 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
- OUT 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 ensure 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 ensure 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.