This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24725A: No battery circuit

Part Number: BQ24725A
Other Parts Discussed in Thread: BQ24725

Hi Sir,

Customer is doing a second generation product without battery, but they would like to share the same circuit as previous generation. In previous generation, they use BQ24725A on their system with a Battery.

The question is that customer would like to know what circuit they could remove if there is no Battery installed?

Thanks,

Patrick 

  • Hey Patrick,

    So the customer would only be using the BQ24725A charger as a load switch to the system? I think this would be a bit overkill for their system.

    Regards,

    Joel H

  • Hi Patrick,

    If the battery is not installed in the new design, there is only a direct power path from the adaptor to the system. Then the customer can connect the adaptor to the system directly. What is the goal for the design to use a battery charger? 

     

  • Hi Eric,

    I agree with you that this is over kill on their new platform(no battery), but as i mentioned before, this is the second generation platform and in their first generation platform, they have battery in it, so they use BQ24725 on their system.

    Customer would like to keep the layout and PCB design, so they want to know which component they could remove if there is no battery installed. 

    So, could you tell me what components that customer could remove? like the mosfet/inductor?

    Thanks,

    Patrick 

  • Hey Patrick,

    I believe the customer can remove the inductor, LSFET, HSFET, the external BATFET, the sensing resistor, the output capacitors on the SRN side, the BTST capacitor, the REGN capacitor, the REGN diode to the BTST capacitor.

    Because this is a battery charger, this configuration has not been fully validated, so the customer will need to test the operation on their side. 

    I would also recommend implementing a way to pull-down the SRN/SRP nodes as well as the BATDRV pin.. 

    Regards,

    Joel H

  • Hi Joel,

    Finally, RD follow your suggestion and modify the circuir as below.

    Could you confirm it OK or not?

    Thanks!

  • Hey Julian, 

    Your circuit configuration should work theoretically, but because we have not validated this configuration, we cannot confirm if you will see unexpected behavior. 

    It appears that this configuration could work. However, I would also suggest pulled SRP and SRN to GND. You will likely not need C24 either as you are no longer sensing the differential voltage across RSR.

    Other than that, I think we will get a better idea of the behavior we can't predict currently once the design is complete. 

    Regards,

    Joel H