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Back up battery performance

UMESH D N
Prodigy 10 points
Other Parts Discussed in Thread: TPS65950

hi,

I  am Umesh, I have question regarding PMIC (TPS65950) power consumtion during backup mode. We are using  HB414IV01E (Seiko instruments) backup battery, Which is having Nominal capacity of 150 uAh capacity @ 5 uA  if operating voltage is  3 to 2 V .

From the datasheet of TPS65950A3 (Table 4.4 in Data Manual) , we can notice that current consumption in backup mode is 2.25uA, Which can be provided by HB414IV01E backup battery .But we are loosing backup battery capacity very quickly not even 6 hours. According to data we have, backup battery must work around 65 hours.

I have question "Is PMIC drawing more current in backup mode?"  

or 

"Is there any other factor of PMIC which decides the Battery performance"

Can you clear this doubt ...

Thank you

Umesh

  • 0
    TI__Intellectual 2045 points

    Umesh,

    i can see two things that can decrease the backup time:

    • VRTC is not in low power mode: consumptiom from specification is for a VRTC in low power mode configuration. If VRTC is not in low power, consumption can be aroud 10µA. Set CK32K_LOWPWR_EN bit to 1 in CFG_BOOT register.
    • backup battery is not charged correctly. default end of charge voltage is 2.5V, you must select the good end of charge voltage accordingly to the backup battery specification. Voltage selection is bone by BBSEL bits in BB_CFG register

     

    regards,

    Alexis