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PT2001 SW diagnostic

Hi,

I would like to ask a question regarding PT2001 SW diagnostic code. I was wondering if anyone can help me out.

I am working STG detection and differentiating from HS and LS faults in microcode.

what i did so far is that switch on HS vbat ON for a short period of time, and check if HS Vds, and tell it is LS fault or HS fault.

But this doesn't seem to work. Because it detects always as HS fault even i apply STH on LS drain.

how would you solve for differentiating STG fault from HS (srouce)and LS (drain)?

thank you so much,

Atika

Re: PT2001 SW diagnostic

Hello Atika

Good day!

The behavior you are observing is expected. A short to ground applied at the low-side drain can also trigger the high-side VDS diagnostic when the VBAT high-side is turned on. This happens because current flows from VBAT through the high-side MOSFET and load into the grounded low-side drain, causing the high-side VDS threshold to be exceeded.

Therefore, briefly enabling the high-side cannot reliably determine whether the physical short is located at the high-side source or the low-side drain. For this topology, both faults can produce the same electrical condition at the PT2001 sense inputs.

The recommended approach is to identify the short-to-ground during the idle diagnostic phase, with both HS and LS MOSFETs off, using the HS VSRC and LS VDS feedbacks. If both feedbacks are low, the result should be classified as a “load-path short to ground.” The PT2001 can detect the fault, but it cannot uniquely locate it on the HS-source side or LS-drain side without additional external sensing or isolation circuitry.

I hope this information has helped you, please let me know if you need help with anything else.

Have a great day and best of luck.