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[SOLVED] Reverse polarity protection using N-channel MOSFET

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tomerbr

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Hi Guys,

I need to protect my circuit from reverse polarity.
The relevant part of the circuit if an MPPT charger for a battery.
The input is a solar panel.

The voltage of the panel is to high for the MOSFET so I need a Zener diode to reduce the voltage.
My question is how to connect the Zener in this case?

I attached two circuits, does it matter if I use the left one or the right one?
Other ideas or comments are appreciated.

V+ and V- are the solar panel connections. GND is the circuit GND

Thanks,
Tomer
 

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  • Reverse Polarity Protection2.JPG
    Reverse Polarity Protection2.JPG
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How is the battery connected?
 

The battery is connected to the MPPT output.
What you see is the MPPT input.

See attachment below for the complete circuit (not fully designed yet).

The question is what is better (if there is any difference) for the Zener.

Reverse Polarity Protection3.JPG
 

Zener diode needs to be connected between gate and source to protect the transistor. The other circuit doesn't disconnect a reversed power source at all.

It's not quite plausible to have an efficient MOSFET protection in the V- line and another series diode in the V+ line.
 
Thanks.
That was helpful.
As for the diode, you are right - it is a remanent of an old design, it will be removed.
 

My idea here is that: Reverse Polarity can be done using Diode. By rectifying the input with a full bridge rectification, before using N- Channel MOSFET to ensure full flow of current at the right polarity and to avoid diodes voltage. Thanks
 

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