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Question

I used to use the Chinese DW01A as a protection circuit for prototyping. The initial prototype worked and I have to switch to a western chip now.

For this I have chosen AP9211 because it is very similar to the DW01A. It even has the P and N Channel MOSFETS inside the IC so that is another advantage.

However something about the typical application circuit of AP9211 bothers me. It shorts the negative terminal of the battery to ground. This was not the case in the DW01A and I don't really understand the reason for this. Wouldn't this defeat the purpose of the protection IC? I would appreciate any explanation, as this leaves me scratching my head.

Here are the typical application circuits and the block diagrams:

DW01A:

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AP9211:

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Links to datasheets:

https://www.diodes.com/assets/Datasheets/AP9211.pdf

http://hmsemi.com/downfile/DW01A.PDF

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    \$\begingroup\$ Probably the data sheet was written by a SPICE user. The simulator requires one grounded node. \$\endgroup\$
    – Whit3rd
    May 23 at 16:55
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If you just erase the GND symbol in the AP9211 schematic you get the DW01A circuit.

In other words, the GND symbol in the AP9211 diagram just indicates where the negative terminal of the battery goes - nothing more. The ground for the circuit powered by the battery is "P-" in the AP9211 schematic and labelled "BATT-" in the DW01A schematic.

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  • \$\begingroup\$ Thanks for the reply, I think so as well but I wasn't sure. That is kind of a weird way to write it imho. When I see the ground symbol I think it is the global ground of the PCB. \$\endgroup\$
    – Emre Mutlu
    May 23 at 16:54

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