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BQ25792: BQ25792 help check the schematic

Star Xu
Genius 9645 points
Part Number: BQ25792

Hi

The customer design the schematic.

12V/2A supply to VBUS then the chip is damaged, Please help check the schematic.

Thanks

Star

  • 0
    TI__Guru**** 154216 points

    Hi Star,

    For 4S/750kHz, we recommend a 2.2uH inductor to reduce peak inductor current.  Also, we have only tested up to maximum output power with 3x10uF 25V on PMID and 5x10uF 25V on SYS.  25V rated capacitors de-rate significantly at 4X=16.8V.  You might need more capacitance on PMID and SYS.  The VBUS, PMID and SYS 0.1uF capacitors need to be placed as close as possible to those pins and GND, with no vias for the PMID and SYS 0.1uF capacitor.  Also, no vias for the PMID and SYS bulk capacitors. The recently updated EVM user's guide shows the recommended layout.

    Can you give more info on the operating condition at which the charger was damaged?  What charger functions are no longer operating?

    Regards,

    Jeff 

  • 0 in reply to Jeff F
    TI__Genius 9645 points

    Hi Jeff

    Thanks for your reply.

    After change 2.2UH (IHLP2020BZER2R2M11) inductance, then disconnect all the loads and supply 15V/0.1A, after power-on, a slight noise is heard, and there is a smell of burning components.

    Does the circuit have other problem need to be improved?

    Thanks

    Star

  • 0 in reply to Star Xu
    TI__Guru**** 154216 points

    Hi Star,

    Other than needing more capacitance at PMID and SYS, I see nothing wrong with the schematic.  Can you forward the layout?  Is a battery attached at power up?  Can you send scopes shots of VBUS, VSYS and VBAT and/or I2C read of the status and fault after start up?

    Regards,

    Jeff