Other Parts Discussed in Thread: BQSTUDIO
Tool/software:
Subject: BQ76952 – OCD1/OTD protection does not latch off (DSG FET repeatedly toggles on/off)
Description:
We are testing the BQ76952 under over-current discharge and over-temperature discharge conditions, but the protection behavior does not match our expectation.
Protections:OCD1:Threshold = 280 A
Protections:OCD1:Delay = 400 ms
Test Condition:
When applying a 290 A load with an electronic load:
When OCD1 (Over-Current in Discharge 1) is triggered, the expected behavior is that the DSG FET should turn off and remain latched off.
However, in practice, the DSG FET turns off momentarily and then immediately turns back on. After the OCD1 delay time, the same cycle repeats continuously (the attached oscilloscope image shows the DSG pin waveform).
The same phenomenon is also observed with OTD (Over-Temperature in Discharge).
Additional Observations:
During this repeated toggling, if we send the command 0x0093 DSG_PDSG_OFF(), the DSG FET turns off and stays off as expected.
If the OCD1 threshold is configured to 40 A instead of 280 A, the protection operates correctly: the DSG FET turns off and remains latched off at the threshold.
Question:
We would like the DSG FET to remain latched off once OCD1 or OTD protection is triggered (not to recover automatically).
Is there an additional configuration (Recovery Mode, Protection Recovery settings, or other registers) required to force the DSG FET to stay off?
Why does the behavior differ between high threshold (280 A) and low threshold (40 A)?
