MP2797DFP-0000-T Soft-On Causes FET Driver Fail

Battery Management
1

I am using the MP2797 on a custom BMS board and am facing an issue with the Soft-On feature.

Issue:

  • When Soft-On DSG and Soft-On CHG are disabled, the CHG and DSG MOSFETs turn ON normally.

  • When I enable Soft-On DSG, Soft-On CHG, and SC Removal Detect Soft-On, the MOSFETs do not turn ON and the device reports FET Driver Fail.

My hardware/configuration:

  • Battery voltage: 50 V

  • Current sense resistor: 1 mΩ

  • Load: 60 Ω resistive load (approximately 0.83 A)

  • SC Deglitch Time: Maximum setting

  • MOSFETs operate correctly when Soft-On is disabled.

Questions:

  1. What conditions can cause FET Driver Fail during the Soft-On sequence?

  2. Does SC Removal Detect Soft-On have any specific hardware or configuration requirements?

  3. Are there recommended settings for SC Current Limit Soft-On and SC Deglitch Time for a 1 mΩ sense resistor?

  4. Which status or diagnostic registers should I read to determine why the Soft-On sequence is aborted?

  5. Is there a recommended procedure to debug Soft-On failures on the MP2797?

Any guidance or recommended register settings would be greatly appreciated.

Thank you.