💡The Problem :

Over-voltage events are common in DC-powered electronics—whether caused by unstable adapters, lightning surges, or faulty power supplies. Even a brief spike can permanently damage microcontrollers, sensors, and other sensitive components.

🔌The Solution :

Using a MOSFET in combination with an Over-Voltage Protection (OVP) IC ensures your circuit automatically disconnects power when voltage exceeds a safe threshold. The OVP IC monitors the input and drives the MOSFET gate accordingly to block harmful voltages.

🛠️ Practical Example

Suppose you’re building a 5V smart irrigation controller for rural use, powered via a 12V SMPS. If the SMPS fails and pushes 12V directly to your 5V line, your ESP32 module could be fried. Adding a P-channel MOSFET controlled by an OVP IC (like AP4310 or similar) disconnects the load when voltage rises above, say, 5.6V—saving your circuit.

🔢 Sample Calculation

Let’s say your OVP threshold is 5.6V. You need:

• P-MOSFET rated for at least 20V Vds and 3A Id

• Gate pull-up resistor: 10kΩ

• Gate resistor (to control switching speed): ~10Ω
  Power dissipated when ON:

P = I² × Rds(on) = (2A)² × 0.05Ω = 0.2W (well within safe range)

 

🛒 Product Suggestions (Made in India)

• MOSFET

• Flux – for clean, reliable solder joints

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