RC snubber and RCD clamp
Extract parasitic L/C from two ring measurements, or size a flyback leakage-energy clamp.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Parasitic extraction: CP = Cadded / [(f0/f1)² − 1]; LP = 1/[(2πf0)² CP]
Assumptions
- Added capacitance changes only C in the same single-mode ring. Probe capacitance is included in the inferred parasitic capacitance.
- R = √(L/Cpar) is an initial damping choice. Full voltage charge/discharge gives P≈Csnub V²fs; verify actual waveform, pulse rating and damping on hardware.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Network
- rc
- Original ringing frequency
- 20000000 Hz
- Ringing frequency with added capacitor
- 10000000 Hz
- Test capacitor added to ringing node
- 3e-10 F
- Snubber C / inferred parasitic C
- 3
- Switched node voltage
- 100 V
- Switching frequency
- 100000 Hz
- Leakage inductance for RCD mode
- 0.000003 H
- Leakage initial current
- 2 A
- Reflected output voltage
- 60 V
- Clamp voltage above supply
- 100 V
- Allowed clamp ripple
- 10 V
- Recovery charge included in clamp
- 0 C
Results
- Snubber / clamp resistance
- 79.5775 Ω
- Snubber / clamp capacitance
- 3e-10 F
- Inferred parasitic capacitance
- 1e-10 F
- Inferred ringing inductance
- 6.33257e-7 H
- Estimated resistor dissipation
- 0.3 W
- Initial resistor pulse current
- 1.25664 A