Reverse polarity mistakes—like swapping battery terminals—can silently kill sensitive electronics. For prototypers and engineers, a simple error can mean a burnt PCB or dead microcontroller. Luckily, there’s an elegant fix using a MOSFET.

The Problem: Wrong Polarity = Instant Damage

If your power connector is plugged in backward, current may flow the wrong way. In devices like motor drivers, sensors, or IoT boards, reverse voltage often causes irreversible damage within seconds.

The Solution: Use a P-Channel MOSFET as a Polarity Protector

Instead of using a diode (which wastes voltage), a P-Channel MOSFET placed with its source to input and drain to load allows current to flow only when polarity is correct. If polarity is reversed, the MOSFET stays off—no damage done!

Practical Example: Battery-Powered Sensor Board

A hobbyist connects a 12V battery to a soil sensor node. By mistake, the terminals are reversed. Thanks to a P-channel MOSFET, no current flows, and the board stays safe—no blown ICs.

Sample Calculation: Voltage Drop Comparison

• Schottky Diode Drop = ~0.4V → Power loss at 1A = 0.4W

• MOSFET Drop ≈ 0.05V → Power loss = 0.05W → Efficient & cooler

Product Suggestions – Made in India

P-Channel MOSFET for polarity protection:

MOSFET Modules for prototyping:

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