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Buck / Boost Converter

A buck steps down (D = V_out/V_in), a boost steps up (D = 1 − V_in/V_out). Size the inductor so the ripple current is about 30% of the output current — too little wastes size, too much wastes efficiency.

Topology

Input voltage (V)

Output voltage (V)

Output current (A)

Efficiency

Inductor (µH)

Switching frequency (kHz)

Output capacitor (µF)

Duty cycle

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Inductor ripple ΔI

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Ripple vs Iout

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Peak inductor current

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Output ripple

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Continuous-conduction mode, ideal components. Output ripple shown for the buck only; boost ripple is set mainly by the capacitor ESR and the load step. Add ESR ripple (ΔI × ESR) in both cases.

A helper, not a substitute for engineering judgment. Verify against the governing standard.