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Automatic battery charging when adapter input is present while load is disconnected from the battery

Esakkimuthu Shanmuganathan
Intellectual 285 points
Other Parts Discussed in Thread: BQ25713, BQ24610

Hi,

I am looking for the chip solution to implement the below logic as shown in the figure. There, the battery is 14.8V and its cut-off voltage is 12.8V. My board will have 24V DC adapter input to charge the battery. Since the battery charging circuit is located inside the battery, it is enough if we give a 24V to charge the battery. The battery charging circuit converts this 24V to 16.8 V to charge the 14.8V battery. In our application, the battery is the only source to supply the load and the 24V will not supply the load, and we don't want the battery to supply the load while it is charging. So, we want to detect whether the 24V adapter input is present or not, if yes, we want to close the path between the 24V adapter and the battery and open the path between the battery and load, if not, the switch between the battery and load will close and supply the load. Please suggest if any solution you have to do the above. 

Thanks,

Muthu

  • 0
    TI__Genius 10855 points

    Hi Muthu, 

    Thanks for reaching out on E2E!

    We have a few power mux devices that can choose between two inputs to determine the output. However, our current portfolio doesn't support OTG (on-the-go), which is the behavior you mentioned to charge the battery but also have the battery supply the downstream load.

    It sounds like a battery charger might be a better option here rather than a switching solution. I'm looping in the battery charger team to comment here.

    Thanks,

    Arthur Huang

  • 0 in reply to Alpha H
    TI__Guru**** 152856 points

    Hello Muthu,

    If you have I2C host, the BQ25713 can do the above.

    If you need standalone with the external MUX switches, BQ24610 might work for you.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 285 points

    Hi Jeff,

    Thanks.I did a mistake in the previously attached diagram. Please refer the below diagram that helps to understand my application better.

    In the above diagram, I have shown both charging and battery pack output (14.8V) as a separate path. As I said, I do not need a battery charger IC as you suggested because the battery pack itself has a battery charging circuit inside in it. If I feed 24V at the battery charging terminal, the charging circuit inside the battery pack will regulate 16.8V to charge the 14.8V battery.

    In my case, I want to control only the charging path and the battery output path as below.

    When the adapter input is present,

    1. Close Tthe load switch S1

    2. Open the load Switch S2 to disconnect the load

    When the adapter input is not present,

    1. Open the load switch S1

    2. Check the battery for its cut-off voltage, 13V. If it is well above the 13V, close the load witch S2 to connect with the load.

    Please suggest if any chip solution if you have...

    Thanks,

    Muthu

  • 0 in reply to Esakkimuthu Shanmuganathan
    TI__Guru**** 152856 points

    Hi Muthu,

    In that case, I suggest the BQ24610 with the external MUX switches.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 285 points

    Hi Jeff,

    Well, you are telling to do not use pins and its related components for battery charging (marked as a square in the picture).In that case, I can see whether my adapter is present or not. In the absence of adapter, BATDRV signal goes low to drive the battery PFET Q4 and I will see the battery voltage at Q4 source pin to supply the load. It looks that it will work for my application. Please correct me if my understanding of the above is wrong. Ignoring the pins and components related to the battery charging will not affect the functionality that I want to do?

    Thanks,

    Muthu

  • 0 in reply to Esakkimuthu Shanmuganathan
    TI__Guru**** 152856 points

    Muthu,

    The highlighted FETs are the buck converter FETs and they are required to charge the battery.

    Regards,
    Jeff