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Selection Guide2026-08-07 · 7 min read

How to Select Magnetic Core Material for High Frequency Applications?

Quick AnswerFor 1–100MHz power applications, evaluate core loss density, permeability stability, saturation flux density and cost. FeNi metal alloy cores offer Bs ≥1.5T with stable permeability for MHz metal inductors; ferrite fits low-power >500kHz designs; Sendust and MPP suit mid-frequency EMI and filter roles. Define frequency, current, temperature and loss budget before choosing.

The switching frequency of power electronics keeps climbing — AI GPU VRMs, server power, and compact chargers now operate in the 1–100MHz range. At these frequencies the magnetic core, not the copper winding, usually sets the limit of efficiency and size. Here is a practical selection method.

Start with three numbers

  • Switching frequency (MHz): drives core loss and material choice
  • Peak current (A): decides whether saturation (Bs) is the constraint
  • Temperature budget (°C): ferrite loses permeability near Curie temperature

Compare the main core materials

PropertyFeNi (Iron Nickel)FerriteSendustMPP
Saturation Bs≥1.5T0.3–0.5T~1.05T~0.75T
Permeability range14–160300–1500026–12514–550
Core loss @100kHz≤300 kW/m³Very low (<100kHz–1MHz)ModerateLow
Temp stabilityExcellent (−40 to +180°C)Fair (Curie limit)GoodGood
Typical useMHz metal inductors, AI GPU VRM, EVLow-power HF, transformersEMI filters, PFCFilters, precision inductors

Why FeNi for MHz metal inductors

AI GPU and server power rails need high current at high frequency without saturation. FeNi powder cores combine Bs ≥1.5T with a distributed air gap, so inductance remains stable under heavy DC bias while core loss stays bounded at MHz switching. That is why YUTE’s MHz metal inductors (1–100MHz, 0.047–6.8µH) target AI accelerators such as H100 and B200.

Selection checklist

  • Current is high and DC bias is large → prioritize Bs and bias stability (FeNi)
  • Frequency is above 500kHz and power is low → ferrite is cost-effective
  • EMI filtering / PFC → Sendust or MPP for controlled permeability
  • Temperature swings or automotive grade → require AEC-Q200 qualified materials
  • Prototype first: request samples and measure loss and temperature rise at your real operating point

YUTE Magnetics offers free technical evaluation of core material selection. Send your frequency, current and size targets and our engineers will respond within 24 hours.

Dive deeper into Fe-Ni material properties and the YTFN series in our High Flux Cores Guide, or compare ferrite options in the Ferrite Core Guide.

Related Applications

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