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BQ25750: ACDRV Can not turn on the Mosfets

hakan özkahraman
Prodigy 30 points
Part Number: BQ25750

Tool/software:

Hello,

During the power up from the 24V source, ACDRV pin produces 10V but it is not sufficient to turn on the mosfets in the input. The another problem is, IC can not produce REGN voltage. What reason can it be?

  • 0
    TI__Mastermind 30985 points

    Hello Hakan,

    Thanks for working with this. I have a few questions to help us debug why the FETs aren't turning ON:

    • With the circuit powered OFF, can you use a continuity meter to make sure ACDRV connects the gate of the ACFETs?
    • Do the BATFETs turn ON when there is just the battery?
    • Is ACDRV being measured with respect to GND or the source pin of the ACFETs?

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    Prodigy 30 points

    Hello Ethan,

    Yes, I checked it; it is connected. Now Battery is not exist, so I can try it in next week. ACDRV pin has 10V respect to GND, it has about 2V respect to Source pins and C45 has about 8V (difference 10-2V).

    Best Regards

    Hakan Özkahraman

  • 0 in reply to hakan özkahraman
    TI__Mastermind 30985 points

    Hello Hakan,

    Thanks for the test information. It looks like ACDRV doesn't have enough strength to drive these FETs. I've got a few testing suggestions:

    • Can you remove Q1, Q2, and Z1? This will show there's a problem with the FETs if ACDRV rises up to about 10V with respect to VAC. If ACDRV remains the same, the IC might be damaged.
    • Can you replace the BQ25750 IC? This will show if the IC has been damaged.

    Best Regards,
    Ethan Galloway