Common Mode Chokes: Selection and Application Notes

Common mode chokes are essential for suppressing common-mode EMI in power lines, data interfaces and automotive networks.

How they work

A common mode choke consists of two windings on a single magnetic core. Differential currents cancel magnetically, while common-mode currents add and encounter high impedance.

Selection criteria

• Impedance at the noise frequency: check the datasheet impedance curve, not just the nominal value.
• Rated current: ensures the choke does not overheat or saturate at operating current.
• DCR: keep copper loss acceptable for efficiency-sensitive designs.
• Package: surface-mount chokes cover most designs up to 10 A; through-hole parts handle higher current.

For CAN, USB and Ethernet filtering, ANFULLY stocks a full range of common mode chokes with impedance curves available for download.

This article was written by fifi. Reproduction with attribution is welcome.