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BQ25720: charger solution for 4S/18V battery voltage

Part Number: BQ25720

Hi Team,

My customer would like to use 4.5V/per cell on their 4S system(NB) so Vbat will up to 18V.

As far as I know, hybrid power boost charger cannot meet customer's requirement because Vbat will higher than adapter voltage in worst case.

Therefore, we are considering to buck-boost charger. But I am not sure BQ2572x can meet customer application or need to use 5S solution BQ2573x?

Please let me know if your have any suggestion. Thank you.

Best regards,

Hardy

  • Hi Hardy,

    BQ25720 is suitable for 1-4S battery. If 5S is needed, I would recommend switching to BQ2573x. 

    Both are buck-boost controllers suitable for VIN>=VBAT and VIN<=VBAT.

    For major sections of product design, I recommend starting with EVM or prototype boards first.

    https://www.ti.com/tool/BQ25720EVM 

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory

  • Hi Peng,

    Thanks for your comments.

    Normally, we calculate typical 1S cell to 4.2V. But customer's new battery is 4.5V. So, the battery voltage for 4S cells is 18V and this value is  between typical 4S(16.8V) and 5S(21V) cells. Therefore, we should suggest customer to use BQ2573X. Please correct me if my thought is wrong.

    Best regards,

    Hardy

  • Hi Hardy,

    You can still recommend BQ25720 to see how your customer think. Please see circled paragraph below.



    However, I do want to mention that SYSOVP minimum in characterization is 19V with typical value being 19.5V. 





    If they are not comfortable, then they can use BQ2573x.

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory