Snubber Circuit Calculator

A snubber circuit suppresses the voltage spikes and high-frequency ringing that occur when a switch turns off in power electronics — protecting components and reducing electromagnetic interference. Enter your maximum input voltage, switching frequency, peak current, rise time, circuit inductance, ringing frequency, and desired power dissipation, then select either an RC or RCD snubber type. The Snubber Circuit Calculator returns the required snubber capacitor value, along with the snubber resistor, power dissipation, and damping factor.

V
Hz

Enter in Hz (e.g., 100000 for 100kHz)

A
ns
μH
Hz

Measured ringing frequency at switch node

W

Results

Snubber Capacitor

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Snubber Resistor

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Power Dissipation

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Damping Factor

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Frequently Asked Questions

What is a snubber circuit and why is it needed?

A snubber circuit is used to suppress voltage spikes and ringing in switching circuits. When inductive loads like transformers, relays, or motors are switched off, they create high voltage spikes that can damage components and cause EMI issues.

What's the difference between RC and RCD snubber circuits?

RC snubber circuits use only a resistor and capacitor in series. RCD snubbers add a diode to provide better energy recovery and improved efficiency by allowing current to flow in only one direction.

How do I measure the ringing frequency in my circuit?

Use an oscilloscope to observe the switch node voltage during switching transitions. The ringing frequency is the oscillation frequency you see immediately after the switching event.

What happens if my snubber capacitor value is too large?

An oversized snubber capacitor can slow down switching transitions, increase switching losses, and may cause additional ringing. It's important to use the calculated value for optimal performance.

How does rise time affect snubber design?

Faster rise times (shorter duration) create more severe voltage spikes and require smaller snubber capacitors but may need lower resistance values to provide adequate damping.

Can I use standard capacitor values instead of the calculated exact value?

Yes, you should use the nearest standard capacitor value. It's generally better to choose a slightly larger standard value than a smaller one to ensure adequate spike suppression.

What power rating should I choose for the snubber resistor?

The resistor should be rated for at least 2-3 times the calculated power dissipation to ensure reliable operation and account for variations in operating conditions and component tolerances.