BQ76952: Using low-side FET and DCHG turn off abnormally while charging

quan mai

Part Number: BQ76952

Hi all，

I have met some problems and I need your help.

I used DDSG and DCHG for low side FET control, when I wake up BQ76952 from shutdown mode to normal mode by TS2,

1、The first time I turn on the DC sourse. When charging current occurs, DCHG would turn off for a short time(about 100mS), and DCHG would recover turn on automatically.

2、When I turn off the DC sourse, and then the second time I turn on the DC sourse.DCHG would operate normally.

Please look at the picture as below.

e.g.

Ch1: Pack+--Pack-

Ch2: Current

Ch3: DDSG

Ch4: DCHG

1 年多前

0 quan mai 1 年多前

Prodigy 30 points

Part Number: BQ76952

大家好，

我用BQ76952的低边开关控制模式，电池为11串，用DDSG和DCHG控制低边MOS。

电池电压38V，在BQ76952第一次开机，当接入DC源充电（设置40V，10A），在出现充电电流时，约200mS后DCHG会自动断开100mS，并且DCHG会自动恢复输出闭合充电MOS，而DDSG无异常断开，另外软件上也没有查到故障上报。每一次都是BQ76952第一次开机后，启动充电电流才会有问题，当第二次或者第三次再接入充电电流时，DCHG就不会出现异常断开的动作。

请教下大家有没有好的建议，谢谢！

下面是测试波形：

Ch1: Pack+--Pack-

Ch2: 电流

Ch3: DDSG

Ch4: DCHG

0 Star Xu 1 年多前

TI__Guru*** 130456 points

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0 Star Xu 1 年多前回复 Star Xu

TI__Guru*** 130456 points

您好，是否方便提供完整的电路。

Since you are using low-side driving, I am guessing that means you don't have a predischarge/precharge circuit in your design. It could be that the initial inrush current when the FETs are first flipped on is enough to trigger an SCD or OCD fault. Could you check to see whether any faults trigger on the device when it goes high unexpectedly?