Why does a boost converter output more voltage than the input?

During the on interval the inductor stores energy from the input. During the off interval the inductor voltage adds to the input through the diode, charging the output capacitor above Vin.

Why limit the duty cycle slider below 100%?

The ideal CCM equation tends to infinity as D approaches 1, but real converters saturate, hit current limits, and lose diode transfer time. The simulator keeps the range educational rather than destructive.

Boost Converter

Step-up DC-DC converter: Vout = Vin/(1−D), inductor current ripple, MOSFET/diode states, CCM/DCM hint, and output ripple.

The model is an ideal asynchronous boost converter with a simple DCM estimate. It omits switch and diode drops, switching loss, reverse recovery, inductor saturation, right-half-plane-zero control effects, and transient load response.

Live graphs

About this model

A boost converter raises a DC input by storing energy in an inductor while the MOSFET is on, then releasing that energy through the diode into the output capacitor and load. In ideal continuous-conduction mode the gain is Vout/Vin ≈ 1/(1-D), and the inductor current ripple is ΔIL = Vin D/(L fs). At light load or low inductance the inductor current reaches zero, so the converter enters discontinuous-conduction mode and the gain depends on load. This simulator shows MOSFET and diode intervals, CCM/DCM boundary inductance, DCM gain hint, average inductor current, output capacitor ripple, and a one-period current waveform.

Who it's for: Power electronics, embedded hardware, battery-powered devices, LED drivers, robotics, and introductory DC-DC converter design.

Key terms

Boost converter
Duty cycle
Inductor current
CCM
DCM
Output ripple

How it works

Boost converter simulator for Vout = Vin/(1-D), inductor current ripple, diode/MOSFET states, CCM/DCM boundary, and output capacitor ripple.

Key equations

CCM: Vout ≈ Vin/(1 − D), ΔIL = Vin·D/(L fs)

Boundary: Lcrit = D(1 − D)²R/(2fs), ΔVout ≈ Iout·D/(Cfs) + ΔIESR·ESR

Frequently asked questions

Why does a boost converter output more voltage than the input?: During the on interval the inductor stores energy from the input. During the off interval the inductor voltage adds to the input through the diode, charging the output capacitor above Vin.
Why limit the duty cycle slider below 100%?: The ideal CCM equation tends to infinity as D approaches 1, but real converters saturate, hit current limits, and lose diode transfer time. The simulator keeps the range educational rather than destructive.

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Boost Converter

Live graphs

About this model

How it works

Key equations

Frequently asked questions

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Live graphs

About this model

How it works

Key equations

Frequently asked questions