Choose a power inductor using the converter's current waveform, switching frequency and thermal environment. TDK and Murata both offer multiple constructions and package sizes, so brand-wide rankings are not useful. Matching nominal inductance and footprint is only an initial filter for an alternative.
Choose the appropriate inductor category
TDK describes its VLS series as wound power inductors with magnetic shielding. Murata's power-inductor selection guide presents different constructions and series, including LQH options. Use the individual part's data and curves to narrow those broad families.
Keep energy-storage inductors separate from signal inductors and ferrite beads. Their intended behavior differs even when the package looks similar. Start from the regulator manufacturer's permitted inductance range and operating mode, then evaluate a specific candidate.
Separate saturation from thermal current
Calculate peak current as well as average and RMS current for the expected operating envelope. Saturation current is tied to a stated reduction in inductance; temperature-rise current is tied to a stated heating criterion. Manufacturers or series can use different definitions, so compare the conditions printed beside the values.
Review inductance under DC bias and across temperature. Include startup, current limiting and load transients where relevant. A part that carries the nominal load may still lose too much inductance during a peak, changing ripple current and stressing the power stage.
Assess losses and test the actual layout
DC resistance contributes to copper loss, but it is not the entire loss budget at the converter's switching frequency. Consider core and AC losses using the manufacturer's available data or design tools. Lower resistance may require a larger component, while a smaller part may run hotter.
Check component height, land pattern, placement and coupling to sensitive circuits. Shielding does not remove every layout concern. Measure temperature, efficiency and output ripple on the production PCB with the intended enclosure. Also investigate audible noise if the converter enters operating modes that excite mechanical vibration.
Frequently asked questions
Can another 4.7-microhenry part replace the approved inductor?
Only after comparing tolerance, biased inductance, current definitions, resistance, losses and dimensions. The converter must still satisfy its electrical and thermal acceptance limits with the exact alternative.
Is the largest current rating always preferable?
No. Check which rating is being quoted and under what conditions. A design needs adequate saturation and thermal margin while meeting size, efficiency and cost requirements.
Send SENICO your inductor RFQ with full manufacturer codes, quantity, approved alternatives and required date. Stock, price and lead time require quotation confirmation.