Boost Converter Reference

Core equations (CCM, ideal)

V_out / V_in

= 1 / (1 − D) — where D is duty cycle of switch

D

= 1 − V_in / V_out

Inductor ripple ΔI_L

= V_in · D / (L · f_sw)

Output cap ripple ΔV_out

= I_out · D / (C_out · f_sw)

Min inductor for CCM

L_min = V_in · D / (2 · I_out · (V_out/V_in) · f_sw)

Topology

• Switch (low side) closes → inductor stores energy.
• Switch opens → inductor forces current through diode into load + cap.
• Output voltage is always greater than input (ignoring drops).
• Uses one inductor, one diode, one switch, and one output capacitor.

Component sizing tips

• Inductor: pick ΔI_L ≈ 30% of I_L(avg). Higher L = less ripple, bigger part.
• Switch: handle V_out peak, peak I_L, plus margin. Low R_DS(on) at the required V_DS.
• Diode: Schottky for efficiency under ~40 V, fast recovery above. Rate for V_out + margin.
• Output cap: low-ESR type (ceramic or polymer) for ripple and transients.
• Feedback loop: boost has right-half-plane zero — compensate conservatively; use Type III comp.