Reverse current is one of the most overlooked issues in power supply design—especially when you’re using multiple 12V sources. Whether you’re running motors, lights, or microcontroller circuits, a lack of reverse current protection can lead to expensive damage.

❗ The Problem: Backfeed Can Damage Components

If two 12V power sources—say, a battery and an adapter—are connected in parallel, and one source drops in voltage or fails, current may flow in reverse into the weaker source. This can cause heating, regulator failure, or even fire hazards. Many prototypers miss this issue until something gets burnt!

🛠️ The Solution: Use Diodes or MOSFETs for Protection

You can block reverse current using a Schottky diode, which only allows current to flow one way. A better and more efficient solution is using a P-Channel MOSFET as an ideal diode, which prevents reverse current without a big voltage drop—perfect for low-loss applications.

🧰 Practical Example: Dual Power in Robotics

A hobbyist connects a 12V wall adapter and a 12V Li-ion battery to a robot base. When the adapter is unplugged, current flows back into it from the battery, damaging its internal circuitry. Adding a P-Channel MOSFET solves the issue and protects both sources.

🔢 Sample Calculation: Comparing Power Loss

Using a Schottky Diode:
Voltage drop = 0.4V, Current = 2A
Power loss = 0.4V × 2A = 0.8W

Using a P-Channel MOSFET:
Voltage drop ≈ 0.05V
Power loss = 0.05V × 2A = 0.1W — much more efficient!

🛒 Product Suggestions – Made in India

🔌 P-Channel MOSFET Module – Ideal diode for reverse current protection:

🔧 Schottky Diode – Quick and easy protection method:

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