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BQ76925: VCTL Pin Datasheet Question

Errol Leon6
Expert 5850 points
Part Number: BQ76925

Hello,

My customer has a question about the bq76925 gas gauge:

On page 13 of the data sheet it says: 

The LDO regulator may be overridden (that is, back-fed) by an external-supply voltage greater than the regulated

voltage on V3P3. In this configuration, the bq76925 internal logic and interface circuitry operates from the

external supply and the internal 3.3-V regulator supplys no load current.

 

Customer is assuming that the VCTL pin would connect to the BAT pin.   Is this correct  or should it float?

Thanks!

Errol Leon

Texas Instrument 

Field Applications Engineer

  • 0
    TI__Guru 54715 points
    Hi Errol,
    It may depend on the system configuration.
    If the external regulator is reliable or provides a large load, a pull up resistor or floating may be desired, there would be no pass transistor to control and if the voltage fell the bq76925 will POR.
    If the external regulator is not considered reliable and has a small load, connecting VCTL to BAT would allow the 3.3V regulator to operate if the external regulator voltage fell. In this case the bq76925 would provide the voltage to the system within its capability.
    Consider other cases as needed.
  • 0 in reply to WM5295
    TI__Expert 5850 points
    Hello,

    The customer has given me more details and questions on the application. Could I email it to you? What's your email?

    Best regards,
    Errol
  • 0 in reply to Errol Leon6
    TI__Guru 54715 points
    Hi Errol,
    Management recommends open communication when not proprietary so other users can benefit. You can send a friend request and embed email addresses or other information in them to start a private conversation. there may be other tools as well now.
    Contacting your local TI application engineer may provide more immediate local support, and it could be beneficial compared to this help desk type environment.