What is the formula for Boost Inductor Ripple Current?

The Boost Inductor Ripple Current formula is ΔIL = Vin × D / (fs × L), where ΔIL—Peak-to-peak ripple current (A); Vin—Input voltage (V); D—Switch duty cycle (0–1); fs—Switching frequency (Hz); L—Inductance (H).

What does ΔIL mean in the Boost Inductor Ripple Current formula?

ΔIL is Peak-to-peak ripple current (A).

Boost Inductor Ripple Current

Q: How do you calculate Boost Inductor Ripple Current?

Use the formula ΔIL = Vin × D / (fs × L). During the switch on-time of a boost converter the full input voltage is applied across the inductor, ramping its current up. Enter the values you know in the calculator above and it solves for the remaining variable.

ΔIL = Vin · D / (fs · L)

Calculator

Ripple Current

Input Voltage

Duty Cycle

Switching Frequency

Inductance

Result

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Formula

ΔIL = Vin × D / (fs × L)

Description

During the switch on-time of a boost converter the full input voltage is applied across the inductor, ramping its current up. The peak-to-peak ripple equals the input voltage times the duty cycle (the fraction of the period the switch is on) divided by the switching frequency and inductance. It is the basic relationship for predicting inductor ripple from operating conditions.

Variables

ΔIL — Peak-to-peak ripple current (A)
Vin — Input voltage (V)
D — Switch duty cycle (0–1)
fs — Switching frequency (Hz)
L — Inductance (H)

Practical Notes

For a boost, D = 1 − Vin/Vout. Keep ripple in the 20–40% range of average current to balance core loss, RMS heating, and capacitor stress.

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