Flyback Diode Vs Snubber circuit?

Question

I understand that a flyback diode is used to safely redirect current when a switch turns off, while a snubber (like an RC or RCD network) absorbs voltage spikes to protect the switch. But when should one be used over the other? Are there specific applications where a snubber is better than a diode, or vice versa?

nathan · Answer

Both flyback diodes and snubbers are used to protect switching devices from voltage spikes caused by inductive loads, but they serve different purposes and are chosen based on the specific application:

Use a flyback diode when:

You're switching DC inductive loads, such as relays, solenoids, or motors.
You want to safely redirect the stored energy back into the coil to allow a smooth current decay.
Speed is not critical — a flyback diode slows the voltage collapse, which can slightly delay the de-energizing of the load.

Use a snubber (RC or RCD) when:

You're switching AC loads (flyback diodes don’t work with AC).
Fast turn-off of the inductive load is important — snubbers absorb and dissipate energy rather than redirecting it back into the coil.
You're using high-speed switching (e.g., in SMPS, IGBTs, or triac circuits), where diodes may not be fast enough or appropriate.