Work out boost converter duty cycle instantly with clear inputs, formula shown and shareable results.
A boost converter has duty cycle D = 1 - Vin/Vout, so the higher the step-up ratio the closer duty approaches one. Input current is output power divided by input voltage and efficiency, which is why a low-voltage boost draws far more current than its output rating suggests.
Boost converter
D = 1 - Vin/Vout; Iin = Vout x Iout / (Vin x efficiency)
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.
Duty cycle approaches 100%, leaving no time to transfer energy, while conduction losses rise sharply. Beyond about 5:1 a transformer-based topology is better.
Stepping 3.7 V up to 12 V at 0.5 A needs over 1.8 A in, so the battery, inductor and switch must all be rated for the input current, not the output.