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BQ24616: Question about undercurrent at the input

Austin Do
Intellectual 2175 points
Part Number: BQ24616

Hello team,

How BQ24616 behave when undercurrent condition at the input side?

For example, I_charge is set by 1A and then if adapter provide only 0.5A, how does it operate? 

Best Regards,

Austin

  • 0
    TI__Mastermind 34215 points

    Hello Austin,

    It all depends on your input voltage and battery voltage. As this is a buck charge controller, your final battery voltage has to be less than your input voltage. As such, any step down in voltage is likewise a step up in charge current to maintain the power balance.

    However, you also have a system load directly connected to the input in charging. You need to make sure that the total output power (charge current x charge voltage + load current x load voltage) does not exceed the input power. You can take advantage of using IINDPM, which will place a limit on the input current drawn from the adapter by reducing the charge current as necessary. There is no limit on the input voltage however, and if you overdraw the adapter before you hit IINPDM the input voltage will start to collapse.

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    TI__Intellectual 2175 points

    Hi Michael,

    Thanks for reply.

    The customer has more detailed question.

    Output voltage and current are set by 13V / 1A and then if Adapter provide only 15V / 0.5A(current is limited by any reason), how BQ24616 operate?

    Best Regards,

    Austin

  • 0 in reply to Austin Do
    TI__Mastermind 34215 points

    Hi Austin,

    Here you are requesting 13 W of output power with 7.5 W of input power at the max charge voltage. At the max charge voltage you cannot supply enough power. If your IINPDM is not set to 0.5 A appropriately your input will start to drop. If your IINPDM is set to 0.5 A you will charge the battery with 7.5 W of input power, lowering the charge current as necessary to achieve the power balance.

    Even at the LOWV threshold of 1.55 VFB or 9.6 V Battery you will still be able to supply enough power to charge the battery at 1 A.

    Please make sure you have enough power to charge the battery without overloading the supply and make sure you limit the input current according to the adapter limits.

    Regards,

    Mike Emanuel