One of the most common mistakes in battery-powered designs is reverse polarity connection. Accidentally connecting a battery the wrong way can instantly damage your circuit or even cause fire hazards. Thankfully, there’s an easy fix that protects your project without adding complexity.

🔧 The Problem :

Whether you’re working with Li-ion cells or sealed lead-acid batteries, reverse polarity can fry your microcontroller or power IC. Traditional fixes like diodes introduce voltage drops, reducing efficiency—especially in low-voltage systems.

💡 The Solution :

Use a P-channel MOSFET or ideal diode controller in series with the battery input. A P-MOSFET, when connected correctly, blocks reverse current flow without the voltage drop of a diode.

🔋 Real-Life Example :

Imagine you’re designing a 3.7V Li-ion powered sensor node.

If you use a P-MOSFET with Rds(on) of 20mΩ:

Power loss = I² × R = (0.5A)² × 0.02Ω = 0.005W,

much lower than using a 0.7V drop diode (0.5A × 0.7V = 0.35W).

🛠️ Product Suggestions :

• P-Channel MOSFET

• Ideal Diode Controller

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