July 28, 2026 / SemiMedia / — TDK Corporation has introduced the EP21 series of surface-mount flat-wire double chokes for common-mode electromagnetic interference filtering in DC-DC converters and other low-voltage circuits.

Identified by the ordering-code family B82552J*J021, the series consists of four models with rated currents ranging from 20.3A to 35A and nominal inductance values from 160µH to 640µH.

The components support rated voltages of up to 48V AC or 80V DC and have a line-to-line DC test voltage of 200V. They can operate at their full rated current at ambient temperatures up to 70°C, with current derating required above that temperature.

The EP21 series combines an MnZn ferrite core with flat-wire windings. The winding structure enables typical DC resistance as low as 0.44mΩ, helping limit conduction losses in power circuits carrying relatively high continuous currents.

The four available models provide typical DC resistance values of 0.44mΩ, 0.80mΩ, 1.25mΩ and 1.75mΩ. Inductance and DC resistance are specified per winding. Typical stray inductance ranges from 200nH to 900nH, depending on the model.

Peak common-mode impedance occurs at frequencies between approximately 500kHz and 3MHz across the product range. The components can therefore be used to attenuate high-frequency common-mode noise generated by switching transitions in DC-DC power-conversion systems.

All four models have a footprint of 23.8 × 17.7mm, with heights ranging from 21.6mm to 22.3mm. Underbody terminations reduce the required board area, while a four-pin self-leaded construction is intended to improve mechanical reliability and support surface-mount assembly.

The B82552J2164J021 provides the highest rated current at 35A, together with 160µH inductance and typical DC resistance of 0.44mΩ. At the other end of the range, the B82552J2644J021 provides 640µH inductance, a rated current of 20.3A and typical resistance of 1.75mΩ.

For more information, please visit www.tdk-electronics.tdk.com/en/data_chokes.