TI中文支持网Part Number:BQ24295
我用BQ24295作为我的电池管理芯片，但是不知道为什么在USB供电断开后BQ24295就不再输出VSYS了。在电池刚刚插入的一瞬间，会输出正常的VSYS，但在这之后VSYS就只有0.0几伏的电压了，BAT脚的电压为4.1V。下面是我的设计图：
?? ?：
R22没有焊接在主板，TS角被上拉到3.3V
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Star Xu：
您好，请参考schematic checklist 和 PCB Layout Design Tips
https://e2e.ti.com/support/power-management/f/196/t/878463
https://e2e.ti.com/support/power-management/f/196/t/875388
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?? ?：
我检查了checklist但并没有发现我的设计有哪里错了导致没有VSYS输出
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Star Xu：
您好，正在查询，稍后回复。
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?? ?：
您好，有结果了吗
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Star Xu：
您好，请参考下面内容
1)Can you provide a read of all registers after VSYS drops to 0V? Has the BATFET been forced off (this is checked in REG07 bit 5)?
2)You mention "At the moment the battery is inserted" as part of the test conditions. Is the VSYS = 0V behavior observed in test condition when battery is always connected then device transitions from charging battery to battery powering SYS when USB adapter at VBUS is removed?
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?? ?：
1. I have read the status of REG07. The status of REG07 is as shown below.2. When the battery is always inserted and the USB power supply is plugged in, the system outputs VSYS normally. But if the adapter is unplugged, VSYS quickly drops to about 0.04V.
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Star Xu：
您好，正在询问更了解这款芯片的TI工程师，稍后回复。
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Star Xu：
您好，Based off the REG07 status you shared BATFET is not being turned off. When the device is in battery only mode the BATFET is the only thing between BAT and SYS pins. Therefore, it seems the BQ24295 charger device is not the reason VSYS is dropping. Can you check if the battery protector is preventing the battery from discharging?
An alternate strategy to confirm the issue is not related to the IC is to check if a power supply connected at BAT or a battery simulator, such as a sourcemeter, is able to output to SYS normally when USB power supply is not present at VBUS.
