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BQ76925: On chip regulator overshoot issue

Sheldon He
Expert 8585 points
Part Number: BQ76925

Hi expert,

My customer is using BQ76925 and meets overshoot issue when using internal regulator. This happens in very low rate and is not easy to reproduce in their system.

When external FET switched off, OV on 3.3V rail can reach up to 12V peak as shown below. May I know how to trouble shoot this issue?

Thanks

Sheldon

  • 0
    TI__Guru 54715 points

    Hi Sheldon,

    1. Be sure the transistor is connected as shown.  If the transistor is connected directly to BAT+ a rise in the BAT+ voltage could spike the output.

    2 Use a high gain transistor.  See the application note http://www.ti.com/lit/pdf/slua619 section 6.

    3. Be sure the RVCTL is the recommended value.

    4. Be sure there is no added capacitance on VCTL.

    5. The regulator is slow to respond, see the application note, consider if a filter such as in the application note is needed in the application.