Boost Converter Inductor Selection

Question

Problem: Boost Converter Inductor Selection. Solve this hands-on electronics task on EWskills.

Accepted Answer

1. Component Purpose & Current Calculation

A boost converter steps voltage up — from 3.7V (Li-ion battery) to 12V. The inductor stores energy from the low-voltage input during the switch ON phase, then releases it at a higher voltage during the switch OFF phase.

Key point: in a boost converter, the inductor is on the input side, so it carries the input current — which is higher than the output current.

Input Current Estimation:

Output power = 12V × 0.5A = 6W

Assuming ~85% converter efficiency:

Input current = 6W / (3.7V × 0.85) = ~1.9A average

With ripple current added, peak inductor current can reach ~2.5A or more.

This is why the task requires ≥3A current rating and ≥3.5A saturation — even though the output is only 0.5A.

Required: 10µH · ±20% · Irms ≥3A · Isat ≥3.5A · DCR ≤100mΩ · Shielded · SMD · −40°C to +125°C · RoHS

2. How to Find It on DigiKey

Go to DigiKey.com → Inductors, Coils, Chokes → Fixed Inductors

Apply these filters:

Inductance → 10µH
Current Rating (Amps) → 3A or higher
Current - Saturation (Isat) → 3.5A or higher
DC Resistance (DCR) → 100mΩ or lower
Shielding → Shielded
Type → Wirewound
Mounting Type → Surface Mount
Part Status → Active

Tip: For battery-powered designs, lower DCR is especially important. Every milliohm of resistance wastes power from the already limited battery supply.

3. Key Specifications & What They Mean

Specification	Required	Why
Inductance	10µH	Sets boost converter switching behavior.
Tolerance	±20%	Standard for power inductors.
Current Rating (Irms)	≥3A	Input current is ~1.9A; margin for heating.
Saturation Current	≥3.5A	Peak current with ripple can reach ~2.5A.
DC Resistance (DCR)	≤100mΩ	Minimizes I²R loss; critical for battery life.
Type	Shielded Wirewound	Shielded reduces EMI from switching noise.
Temp Range	−40°C to +125°C	Industrial range.
RoHS	Yes	Compliance required.

Important: In boost converters, always size the inductor for the input current, not the output current. The input current is always higher because the input voltage is lower (power is conserved: Pin = Pout / efficiency).

4. Selecting a Safe, Production-Ready Part

The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?

Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide

5. Filtered DigiKey Link

➡ View Matching Parts — 10µH, Shielded, ≥3A, Isat ≥3.5A, DCR ≤100mΩ

19. Boost Converter Inductor Selection