Interactive simulation
Boost converter simulation
Coil, switch and diode turning 12 V into 24 V — and the input current the load never sees.
Q1 and D1 never conduct together: while Q1 is on the coil is charging from Vin and the output cap alone feeds the load; when Q1 opens the coil adds its own voltage on top of Vin and D1 dumps that into the cap. Volt-second balance makes Vout = Vin/(1−D) as long as IL never reaches zero, and the same power balance forces the input current to be Iout/(1−D) — the coil draws far more amps than the load takes. Drop the load until the orange current touches zero and the converter falls into DCM — at the settings this panel opens with you have to lower L or fsw as well, because the load slider's own floor stops above the boundary: Vout = Vin·(1 + Vin·D²/(2·L·fsw·Iout)) then climbs well above Vin/(1−D), which is why an unloaded boost with no feedback destroys itself. ΔVout is the cap discharging at Iout for the whole time D1 is off, ≈ Iout·D/(fsw·Cout) in CCM with Cout fixed at 100 µF.
