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BQ25150: VDD state when battery is empty

Giuliano FRANCHETTO
Intellectual 380 points
Part Number: BQ25150


Hi,

In a case where the connected battery is empty  (Vbat < Vbatuvlo) and Vin is not present, what is the state of VDD pin ?

From the block diagram, it seems that VDD is always connected to either VIN or VBAT regardless of the condition Vbat > Vbatuvlo, is it correct?

Our use case would be to have a "I'm on ship mode" pin, where this pin shall be high if we are not in ship mode, regardless of the state of the battery, and low when ship mode is entered.

Would VDD do the job?

Regards

Giuliano

  • 0
    TI__Mastermind 21590 points

    Hello Giuliano,

    If VBAT< buvlo and VIN is not present, VDD will be powered off. VDD is a LDO powered with an OR of either VBAT or VIN depending on which is higher. VDD will connect to VBAT only if VBAT is > BUVLO and VIN is absent.

    Yes you can use VDD to signal when the device is in shipmode and when not in shipmode.

  • 0 in reply to Raheem
    Intellectual 380 points

    Hi Raheem

    Raheem said:
    Yes you can use VDD to signal when the device is in shipmode and when not in shipmode

    This assertion seems to be false. If VDD is removed both when VBAT < VBATUVLO and when ship mode is entered, we cannot use it as ship mode signal. VDD low would either mean "battery discharged" or "ship mode" without a way to differentiate them. Am I right?

    By the way, would VDD be low or floating?

    Regards

    Giuliano

  • 0 in reply to Giuliano FRANCHETTO
    TI__Mastermind 21590 points

    Hello,

    If VIN is present when VBAT < VBATUVLO, VDD will be present. 

    VDD will be low. when in shipmode or battery voltage < BUVLO when VIN is absent.