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I'm using the MP2672A (datasheet) 2-cell balanced charger IC for charging 2 li-on batteries. Normal PFET reverse polarity protection (RPP) doesn't work here as the IC has a balance function which connects to the middle point of the 2-cell series setup.

How can I add reverse polarity protection on 2-cell battery charger IC?

Any suggestions would be appreciated!

Current schematic of the charger circuit.

current schematic

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  • \$\begingroup\$ Can you avoid the need for polarity protection? Use a connector which cannot be connected incorrectly? \$\endgroup\$
    – Justme
    Commented Mar 10, 2023 at 18:46
  • \$\begingroup\$ I wish. To be honest, this isn't the biggest concern, but if there was a low hanging fruit way of doing this, I'd like to as these are 21700 single cells that could be inserted manually versus within it's case. \$\endgroup\$
    – Sean
    Commented Mar 10, 2023 at 19:02
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    \$\begingroup\$ That's exactly the reason why products do not have user changeable cells (unless there is only one), but battery packs that can't be connected incorrectly. Or built-in batteries where user can't change them. \$\endgroup\$
    – Justme
    Commented Mar 10, 2023 at 19:11
  • \$\begingroup\$ That's a great point. I'll focus more on that then. \$\endgroup\$
    – Sean
    Commented Mar 10, 2023 at 19:19

1 Answer 1

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I ended up using an NPN transitor to ultimately achieve what I was wanting -

  1. be able to provide reverse polarity protection, and
  2. be able to charge the batteries with the onboard charger IC.

Schematic

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