TDK launches SurfIND, SMD common-mode chokes for rated currents of up to 36 A at high temperatures

January 23, 2025

TDK Corporation (TSE:6762) launches 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 need high-current common-mode chokes (usually large and heavy) can now get an SMD solution. These components can filter common-mode noise for rated currents from 24 A to 36 A at a temperature of +70 °C. With additional cooling, even higher currents can be achieved. 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 250 V (AC), the nominal inductance ranges from 120 µH to 820 µH 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 40 x 38 mm (L x W), with heights of 20.7 mm for A types and 22.3 mm for B types. Their typical resistance ranges from 0.78 mΩ to 2.21 mΩ. Rated inductance drops by less than 10% at rated current with DC magnetic bias at +20 °C.

SurfIND 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 V-0 approved. The special design of the connection wiring eliminates the need for adhesives while self-leading SMD leads ensure easy reflow soldering to PCBs.

Main applications

• Suppression of common-mode interferences
• Switch mode power conversion applications
• Frequency-variable drives

Main features and benefits

• High rated currents at high temperature
• Low profile with defined height dimension
• Self-leaded SMD terminals suitable for reflow soldering
• Ferrite core with epoxy coating and plastic base plate (UL 94 V-0)
• Approx. 0.6 to 1% stray inductance for differential-mode noise suppression