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TPS65930 RTC current

Steve Sinn
Intellectual 435 points
Other Parts Discussed in Thread: TPS65930

How much current does the TPS65930 draw when only the RTC is running.  I am trying to size a coin battery for this purpose?

Thanks,

Steve

  • 0
    TI__Intellectual 2045 points

    Steve,

     

    This parameter is specified in TPS65930 Data Manual page 47(backup current , 2.25uA)

     

    http://www.ti.com/lit/gpn/tps65930

  • 0 in reply to Alexis Piton
    Intellectual 435 points

    Excellent!  Thanks.

  • 0 in reply to Alexis Piton
    Prodigy 90 points

    I sized my battery using the 2.25uA backup current specified on page 47 of TPS65930 Data Manual. I'm getting reports from the field of dead batteries much sooner than expected. I'm using CR1220 coin cell battery that has 35mAh capacity. I am measuring a current draw from the backup battery of 8.9uA, almost 4 times what the datasheet states.

    A few notes:

    1. Inserting the battery into a board that is powered down (Vbat = 0V), there is no significant current draw from the backup battery (Vbackup=3.2V, @0uA).

    2. Power up the board (Vbat = 4.2V) and there is no significant current draw from the backup battery (Vbackup=3.2V, @0uA).

    3. Power down the board (Vbat =0V) and the backup current spikes to 50uA for a second or less and settles at 8.9uA.

    4. Only time I measure 2.25uA current draw from backup battery is when I remove the backup battery (Vbackup=not present) while powered down (Vbat=0), short BKBAT pin to ground, and reinstall the battery (Vbackup =3.2V, @2.25uA) while powered down (Vbat=0). At this point, the time and date are lost so if the current is being used to power RTC, it's not the correct time and date.

    Please help.

    Daven

  • 0 in reply to Daven McCalla
    TI__Intellectual 2045 points

    Hi Daven,

    You have to set CK32K_LOWPWR_EN=1 to enable the 32KHz clock low power mode and decrease the backup consumption to 2.25uA max(1.7uA typical).

     

    regards,

    Alexis