Low Cost Reverse Polarity And Over Current Protection (corrected) -

This circuit provides a robust, low-cost solution for protecting sensitive electronics from two common killers: accidental battery reversal and excessive current draw. By using a P-Channel MOSFET instead of a standard diode, you achieve high efficiency with minimal voltage drop. 🛠️ The Core Components

Protects the MOSFET Gate from high voltage spikes. This circuit provides a robust, low-cost solution for

Ensures the MOSFET stays "OFF" when no power is applied. ⚡ How It Works 1. Reverse Polarity Protection Ensures the MOSFET stays "OFF" when no power is applied

Unlike a standard diode that loses ~0.7V, a (e.g., AO3401 or IRF9540) has very low "on-resistance" (RDSon). Virtually zero heat generation compared to diodes

Virtually zero heat generation compared to diodes.

The Gate is pulled low relative to the Source, allowing current to flow freely to the load.

If current exceeds the limit, the PTC heats up rapidly, its resistance spikes, and it effectively "opens" the circuit until the fault is removed and it cools down. 📐 Circuit Design Value/Part No. Q1 P-Channel MOSFET Reverse Polarity Switch F1 PTC Resettable Fuse Over-current Protection D1 10V - 15V Zener Gate Over-voltage Protection R1 10kΩ - 100kΩ Gate Pull-down 💡 Key Advantages