An IOUT_OC fault was detected because the differential voltage seen on the ISENSE pins reached the IOUT_OC_FAULT_LIMIT.
Possible Causes:
- A fast transient may have occurred. The current supervisor's update rate is 12us.
- IOUT_CAL_GAIN is set too low.
- IOUT_OC_FAULT_LIMIT is set too low.
- If sensing current by inductor DCR, that is not captured by a scope
- Output is shorted to GND.
Remedies and Workarounds
Here are some experiments you can try to narrow things down:
- Changing the output current limits may resolve the problem, but possibly not. There is a deglitched fault response that might help. Set the IOUT_OC_FAULT_RESPONSE to deglitched and set the delay_count to a non-zero value. The delay_count value represents how many 12us periods the supervisor checks for an OC condition.
- Change IOUT_CAL_GAIN to a larger value which will then translate to a lower output current value.
Other Debugging Tips
There are a number of scenarios which can create a IOUT_OC fault. If you have an oscilloscope, perhaps the fastest way to insight is to:
- Trigger the scope on the falling edge of the ALERTB signal, and
- Look at the ISENSE and VSENSE pins at the IC.
The ALERTB signal will be pulled low by the IC at the time of the fault.