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Buck / Boost Converter Calculator

Size the inductor, output capacitor, and peak switch current for a continuous-conduction buck or boost power stage from your input/output conditions and target ripple.

Buck requires Vin > Vout. Values clamp automatically if they cross.

Duty cycle

50.0%

D = Vout / Vin

Inductor ripple current

0.60 A

ΔIL = ripple ratio × IL,avg

Minimum inductor

6.67 µH

L = (Vin − Vout) × D / (fsw × ΔIL)

Minimum output capacitor

25.0 µF

Cout = ΔIL / (8 × fsw × ΔVout)

Peak inductor / switch current

2.30 A

IL,peak = IL,avg + ΔIL / 2

Switching period

3.33 µs

T = 1 / fsw

On-time / off-time

1.67 µs / 1.67 µs

Ton = D × T,   Toff = (1 − D) × T
Buck: D = Vout / Vin
ΔI_L = ripple ratio × Iout
L = (Vin − Vout) × D / (fsw × ΔI_L)
Cout = ΔI_L / (8 × fsw × ΔVout)
I_L,peak = Iout + ΔI_L / 2

Power stage schematic

Buck: series switch, catch diode to ground
VinQSWDLCRLoadVoutGND

Switching cycle

Switch-node voltage and inductor current over two periods