Greetings, I'm trying to come up with a way to protect a buck converter Lithium Poly single cell battery charger against reverse battery polarity by the battery being charged if it is connected backwards. I can't depend on polarized connectors as the user may change them. I have two problems. First, the output filter capacitor is a 100 mfd tantalum. Is 4 volts reverse polarity going to damage it? I'd hate to have to use a non-polar cap. Maybe I could do without it altogether? The second is a little tougher. There is two Schotkey diodes that become forward biased as a direct short when the battery is connected backwards. I tried to put a MOSFET switch in series with the clamp diode but the body diode of the FET becomes forward bias the same way. I guess I could use an NPN to disconnect but then that forward biases the base-collector junction when the battery is reversed which may destroy the processor that is driving it. See page
7 of the pdf file at this link:Any suggestions would be greatly appreciated.
Regards,
Art