Sumida has introduced the CNFC6D33 and CNFC11D57, a pair of surface-mount DC common-mode chokes that suppress electromagnetic interference (EMI) on DC power lines. The company lists traction inverters, onboard chargers, automotive powertrain systems and automotive HVAC, including electric compressors and PTC heaters, among the applications, alongside industrial and consumer electronics.

The smaller CNFC6D33 measures 7.2 × 6.2 × 3.5 mm. Sumida's product listing rates its versions at 1.5 A and 4 A and gives minimum common-mode impedance at 100 MHz of 500 Ω to 1,970 Ω. Typical impedance reaches 2,500 Ω. DC resistance (DCR) is as low as 15 mΩ maximum.

The CNFC11D57 measures 12.3 × 11.3 × 6.0 mm and comes in three impedance configurations spanning 240 Ω to 1,000 Ω minimum common-mode impedance at 100 MHz. The listing rates its versions at 10 A and 16 A, and DCR is as low as 3 mΩ maximum.

Both parts operate from -40° C to +150° C, including self-heating. Sumida's product announcement also lists an 80 V Hi-Pot test voltage.

A common-mode choke's windings impede noise currents that flow in the same direction on both conductors of a line. The DC supply current flows out on one conductor and back on the other, so its magnetic fields cancel in the core and it sees little more than the windings' DC resistance.

Sumida says both parts are RoHS-listed, have provisional AEC-Q200 compliance and are available through its global distribution network. Custom windings are offered for OEM applications. The company's August product announcement had described the chokes as in pilot production.

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