SMD common-mode chokes for rated currents to 36A at high temperatures

TDK Corporation has launched the EPCOS SurfIND series, a new range of current-compensated ring core double chokes for high currents and surface mounting (ordering code: B82725S2*A/B). With SurfIND, customers who prefer reflow soldering (e.g. sandwich packages in telecom equipment, industrial drives, etc.) but require high-current common-mode chokes (usually large and heavy) can now obtain an SMD solution. These components can filter common-mode noise for rated currents from 24A to 36A at a temperature of +70C. With extra cooling, even higher currents can be attained. This is easy to implement as the top side can serve as a direct interface for a heat sink.

For applications with a voltage of up to 250V (AC), the nominal inductance ranges from 120µH to 820µH across seven variants. With stray inductance of up to 1% of the nominal inductance, these chokes also dampen differential-mode noise. All components meet IEC/EN 60938-2 standards and share a compact footprint of 40mm x 38mm (L x W), with heights of 20.7mm for A types and 22.3mm for B types. Their typical resistance ranges from 0.78mOhm to 2.21mOhm. Rated inductance drops by less than 10% at rated current with DC magnetic bias at +20C.

The chokes are mounted on a plastic baseplate, with a ferrite core coated in epoxy to insulate it from the windings; both materials are UL 94 V0 approved. The special design of the connection wiring eradicates the need for adhesives, while self-leading SMD leads ensure easy reflow soldering to PCBs.

Main applications include suppression of common-mode interferences, switch mode power conversion applications, and frequency-variable drives.