DC-DC Converter

Choose a topology — buck, boost, or buck-boost — set the input voltage, duty cycle, inductance, and switching frequency, then watch the output voltage and inductor current ripple update live. The widget flags CCM vs DCM operation so you can see exactly when the inductor current hits zero.

V_in: 24 VD (duty cycle): 0.5 I_out: 2 AL: 100 µHf_sw: 100 kHz

During T_ON (rising)

\small\tfrac{di}{dt} = \tfrac{24-12.0}{100\,\mu\text{H}} = 0.12\;\text{A/µs}

During T_OFF (falling)

\small\tfrac{di}{dt} = \tfrac{-12.0}{100\,\mu\text{H}} = -0.12\;\text{A/µs}

Output voltage

\small V_{out} = D \!\cdot\! V_{in} = 0.5 \!\times\! 24 = 12.0\;\text{V}

Inductor ripple

\small \Delta I_L = \tfrac{(24\!-\!12.0)\!\times\!0.5}{100\text{k}\!\times\!100\mu} = 0.60\;\text{A}

Conduction mode

CCM — Continuous

Minimum inductance for CCM

L_min = 15.0 µH

Quick experiments

Buck 24 V → 12 V. Set V_in = 24 V and D = 0.5 — the output should read 12 V, confirming V_out = D · V_in.
Boost 12 V → 48 V. Switch to boost, set V_in = 12 V and D = 0.75 — the output climbs to 48 V.
Ripple vs inductance. Increase L and watch the inductor current ripple shrink — a larger inductor stores more energy per cycle, smoothing the current.

DC-DC converter topologies

DC-DC converters transfer power from one DC voltage to another with high efficiency (typically 85–95 %) by switching an inductor or transformer at high frequency (tens of kHz to several MHz).

Buck (step-down)

V_out = D × V_in where D is duty cycle (0–1). During the on-time the inductor stores energy; during the off-time it releases energy to the load. Higher switching frequency → smaller L and C values → smaller PCB footprint, but higher switching losses.

Boost (step-up) and flyback

Boost: V_out = V_in / (1−D). Energy stored in inductor during on-time is transferred to output during off-time.
Flyback: isolated topology using a coupled inductor (flyback transformer). Common in offline power supplies for galvanic isolation.

Learn more → DC-DC Converters — Learn