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BQ24620未按设定电压截止充电

各位好

    应用BQ24620给7S1P磷酸铁锂电池组充电,设置的充电截止电压是25.12V,但充到24.2V左右时就显示充电完成了,充电完成时量取的VBAT24.2V,VFB 1.7V;万用表测试了下空载 VBAt的电压是24.2V,示波器测试波形峰值是25V左右但是过程中有跌落,如下图所示

   请问这是什么问题,如何解决

 感谢

 

Star Xu:

您好,The sync buck converter needs to refresh the top FET driver BTST cap by turning on the low side FET. It can't achieve 100% duty ratio. The output voltage will have headroom from the input voltage. The power loss will also contribute to the headroom required for output voltage regulation.

Star Xu:

您好,The sync buck converter needs to refresh the top FET driver BTST cap by turning on the low side FET. It can't achieve 100% duty ratio. The output voltage will have headroom from the input voltage. The power loss will also contribute to the headroom required for output voltage regulation.

Star Xu:

您好,The sync buck converter needs to refresh the top FET driver BTST cap by turning on the low side FET. It can't achieve 100% duty ratio. The output voltage will have headroom from the input voltage. The power loss will also contribute to the headroom required for output voltage regulation.

ZHONG:

回复 Star Xu:

我这边的输入是27V ,我试过将截止电压设置成26V空载测量的电压(均值)还是24.2V左右,接上电池充电,指示充满量取的电压也是24.2V左右

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