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
Ensures the MOSFET stays "OFF" when no power is applied. ⚡ How It Works 1. Reverse Polarity Protection
Virtually zero heat generation compared to diodes. This circuit provides a robust, low-cost solution for
While the MOSFET stays cool, the PTC will get hot during a fault—keep it away from heat-sensitive components like electrolytic caps. To help you select the specific components, tell me: Your input voltage range? The maximum current your device pulls?
Always choose a PTC with a "Hold Current" slightly above your maximum expected operating current to avoid nuisance tripping. ⚡ How It Works 1
Unlike a standard diode that loses ~0.7V, a (e.g., AO3401 or IRF9540) has very low "on-resistance" (RDSon).
The Gate is pulled low relative to the Source, allowing current to flow freely to the load. To help you select the specific components, tell
Can be implemented in tiny SOT-23 or SOIC-8 packages for compact PCBs. ⚠️ Pro-Tips for Implementation Check Vgs: Ensure your MOSFET’s Gate-to-Source voltage ( VGScap V sub cap G cap S end-sub