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BQ76940: Use 0.47uF on REGOUT pin

Statham Su
Genius 4990 points
Part Number: BQ76940
Other Parts Discussed in Thread: BQ76930

Hello Sir:

We put 0.47uf on REGOUT pin and some products had been shipped to the end customer.

Please let us know does their has any side effects on this mistake?

And my schematic shows below.

Looking forward your feedback.

Thanks a lot.  

  • 0
    TI__Mastermind 27321 points

    Hello Statham,

    The REGOUT pin supplies power to the controller IC. It is recommend to use capacitors greater than 1uF. I assume this has been tested. I do not see a big issue here if it was tested. It'd be good to keep it in mind for future schematic revisions/changes. 

    I suggest to look at this video for any other schematic concern. 

    Regards,
    Jose Couso

  • 0 in reply to Jose Couso
    Genius 4990 points

    Hello Jose:

    We have some application reasons forced we need to increase the rising time of VDD, VDD means REGOUT of our circuit.

    And we make some rising time testing which results shows below.

    We prefer to use 0.47uF or 0.68uF and that rising time is around 55.8us to 80.8us.

    Based on our test results, can you help determine what side effects BQ76930 might have?

    Please let us know your recommendations.

    Thanks a lot.

  • 0 in reply to Statham Su
    TI__Mastermind 27321 points

    Hello Statham,

    The REGOUT powers assorted internal circuitry, including the communication buffers and coulomb counter. If there is no external load the capacitor might be on the small range of the recommended values. 



    Section 9 REGSRC Supply from the bq769x0 Family Top 10 Design Considerations shares good information on the REGOUT pin.

    The 1uF is a recommended capacitor value, but if you have tested the device with the chosen capacitors, it shouldn't be a concern.

    Regards,
    Jose Couso