Toroidal Inductors

A toroidal inductor winds magnet wire directly around a closed ring core rather than a bobbin, so the magnetic circuit has no air gap and the flux path stays inside the core material. Because the field is largely contained within the ring, a toroidal design radiates less external EMI and has lower magnetic leakage than a gapped core of the same inductance and current rating — a property that matters wherever the inductor sits close to other components or sensitive circuitry on the same board. The core is available in different materials to trade off permeability, saturation, and frequency response for the application. Winding coverage runs around the full circumference, which keeps the winding length short and the DCR low for a given inductance.