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BQ25792: Battery depletion threshold

M Anand
Prodigy 240 points
Part Number: BQ25792

Hi,

In the datasheet for BQ25792, Section 9.3.8.2 "Dynamic Power Management" it is mentioned that: "The BATFET turns off to exit supplement mode when the battery is below battery depletion threshold." What is the depletion threshold value? I couldn't find that phrase anywhere else in the datasheet. Is it the same as VBAT_SHORT?

And a follow-on question: if the charger enters this state, ie, BATFET off in the absence of any other input sources, ie, VAC1 and VAC2 both not present, is it correct to understand that the charger will be completely powered off and lose all its register settings ?

Thanks,

Best regards,

Anand.

  • 0
    TI__Guru**** 165786 points

    Hi Anand,

    Yes.  The depletion threshold is VBAT_SHORT.  Note that the internal BATFET body diode always connects BAT to SYS.

    Yes. If both battery and input power are removed (below their respective UVLO values), the registers reset to defaults.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 240 points

    Hi Jeff,

    Thank you - understood, re body diode connection.

    A couple of follow-on questions:

    1) Just to confirm: the VBAT_SHORT threshold value given in the datasheet is for the whole VBAT of the pack, correct? That is, the datasheet value of 2.06V for VBAT_SHORT is not on a per cell basis, is that correct?

    2) There is no way to change that depletion threshold to a higher value, correct? I didn't see any easy way to do that, but just that I'd confirm.

    Thanks,

    Best regards,

    Anand.

  • 0 in reply to M Anand
    TI__Guru**** 165786 points

    Hi Anand,

    Regarding 1, yes. not on a per cell basis.

    Regarding 2, no.  We expect the battery pack protector to open the protector FETs if the battery is goes undervoltage.  

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 240 points

    OK, thanks, Jeff.

    Best regards,

    Anand.