Buck & boost DC-DC converter calculator
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Converter configuration
Buck design numbers
Duty cycle
(V_out + V_d) ÷ (V_in + V_d − V_sw)
Inductor value
Minimum for the chosen ripple
Inductor ripple (ΔI)
I_out × ripple fraction, peak-to-peak
Average inductor current
= I_out
Switch peak current
Average + ΔI ÷ 2 — size the switch and sense resistor for this
Average input current
V_out × I_out ÷ (V_in × 90%)
Verify the inductor's saturation current is well above the 2.3 A peak current shown above.
About the model
Continuous-conduction mode (CCM) is assumed: the inductor current never falls to zero. The duty cycle comes from volt-second balance across the inductor, and the inductance is sized so the peak-to-peak ripple stays at the fraction of load you entered. Real designs close the loop with an error amplifier, add input/output capacitance and a compensation network — the inductor here is the minimum for the chosen ripple, not a complete design.
For the parts themselves: DC-DC converters, power inductors and Schottky diodes carry the ratings the datasheet math above needs.
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