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Original question:

BQ25798: System current requirement

BQ25798: Maximum current output from SYS pin

Jim G
Intellectual 685 points
Part Number: BQ25798

Tool/software:

I do not see a clear maximum output current from the SYS pin specification in the bq25798 datasheet.

I did find this old e2e post where someone states that the maximum current the internal BAT to SYS FET can handle is 6A, but wanted to confirm again.

  • +1
    TI__Guru**** 166626 points

    Hi Jim,

    The max output current out of the SW pins is 5A. Even running at 750kHz with 2.2uH inductor, the package gets too hot and triggering the IC's thermal regulation protection before reaching 5A. The max DC battery discharge current from BAT to SYS is 6A.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 685 points

    Thanks Jeff. In reviewing the recommended layout in the datasheet, this IC really doesn't get much opportunity for copper connection on the component layer and relies almost entirely on inner layer connections, so I'm not surprised that it has some thermal limitations.

  • 0 in reply to Jim G
    TI__Guru**** 166626 points

    HI Jim,

    The EVM uses the bottom layer for heat sinking as well but it is not shown above.  This package is expected to use the pins connected to large pours as heat sink.

    Regards,

    Jeff