🔄 The Problem: Understanding Reverse Recovery in MOSFETs

When switching MOSFETs, especially in high-frequency circuits like SMPS or inverters, reverse recovery of the body diode can lead to voltage spikes, heat, and EMI. This happens when the diode doesn’t turn off instantly, causing current to flow briefly in the wrong direction.

🛠️ The Solution: Tune or Avoid Reverse Recovery

You can minimize reverse recovery losses by:

• Choosing MOSFETs with fast body diodes

• Adding external Schottky diodes in parallel to handle reverse current

• Optimizing gate drive timing to reduce overlap in conduction

💡 Practical Example: Half-Bridge Inverter for LED Driver

Let’s say you’re designing a half-bridge LED driver. During switching, the body diode of the low-side MOSFET can cause a reverse recovery spike when the high-side MOSFET turns on. Placing a Schottky diode in parallel helps by clamping the spike and speeding up recovery.

🧮 Sample Calculation: Power Loss Due to Recovery

Assume:

• Reverse recovery charge (Qrr) = 50nC

• Switching frequency = 100kHz

• Vbus = 12V

Loss = Qrr × Vbus × f = 50nC × 12V × 100kHz = 60mW

This adds up quickly with multiple switches!

🧰 Product Suggestion: Use Made in India Components

Try MOSFETs or Schottky diodes for efficient reverse recovery tuning.

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