Synchronous buck: efficiency, ripple, waveforms
Quick calculator for a synchronous buck (step-down) converter. It estimates inductor ripple and capacitor-only output ripple, and plots iL and vout ripple waveforms.
V
V
A
Hz
H
F
SI prefixes accepted (4k7 / 1M / 10m / 220). Upper-case M = mega, lower-case m = milli
ΔIL (p-p)
2.6515A
IL peak3.3258 A
ΔVout (p-p)30.129 mV
Efficiency (est.)99.741 %
Advanced — Rds(on) HS, Rds(on) LS
Ohm
Ohm
History
Press Enter in any field to keep a snapshot here.
Formula
Equations (idealized):
Duty D = Vout / Vin
Inductor ripple ΔIL(pp) = (Vin - Vout) × D / (L × fsw)
Output ripple (capacitive) ΔVout(pp) ≈ ΔIL / (8 × fsw × Cout)
FET conduction loss (R-only) P = Rds(on) × (1/T)∫ i(t)^2 dt
Duty D = Vout / Vin
Inductor ripple ΔIL(pp) = (Vin - Vout) × D / (L × fsw)
Output ripple (capacitive) ΔVout(pp) ≈ ΔIL / (8 × fsw × Cout)
FET conduction loss (R-only) P = Rds(on) × (1/T)∫ i(t)^2 dt
Design notes
Waveforms: iL(t) and vout ripple(t) over one switching period (ESR ignored).
iL(t) [A]
vout ripple(t) [mV] (capacitive only)
Note: efficiency includes only HS/LS FET Rds(on) conduction losses (no inductor DCR, no capacitor ESR, no switching/deadtime/gate-drive losses).