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BQ40Z80: PRECHARGE

Ran Aloni
Expert 2386 points
Part Number: BQ40Z80

Hi all,

will the BQ40Z80 allow 0V charge?

meaning, the PRECHARGE start voltage is set in the data memory flags.

but when the IC doesn't have enough voltage to operate, say VCC= 1V to 5V, will the precharge path stay open by default?

if yes, and I want to prevent that, is there any course of action I can take?

best regards,

Ran

  • 0
    TI__Genius 11535 points

    Hi Ran,

    The BQ40z80 does support 0V charge. Please see the snippet from our TRM below.

     

    Best,

    Jessica

  • 0
    Expert 2386 points

    thanks Jessica,

    allow me to quote:

    "The BQ40Z80 device also supports 0-V charging using either an external precharge FET or CHG FET. If
    [PCHG_COMM] = 1, the gauge enables the hardware 0-V charging circuit automatically when the battery
    stack voltage is below the minimum operation voltage of the device"

    when choosing PCHG_COMM = 1 , the CHG FET will allow the precharge current.

    how can the CHG FET allow 0V charge, when there is no voltage to drive the FET?

  • +1 in reply to Ran Aloni
    TI__Guru** 105760 points

    Hello Ran,

    The voltage is supplied by the adapter, a lower voltage is applied to the FET gate so the battery is trickle charged, this is to prevent damaged to the battery.

    Sincerely,

    Wyatt Keller