TDK has expanded its EMI suppression portfolio with the EP21 series of surface-mount common-mode chokes, developed for low-voltage power electronics. These compact chokes are designed to reduce electromagnetic interference in applications such as DC/DC converters while helping engineers save valuable PCB space.
The EP21 series features a compact package measuring 23.8 × 17.7 mm with heights between 21.6 mm and 22.3 mm. Its underbody terminal design reduces the required mounting area compared to traditional chokes, while a four-pin layout improves mechanical strength and soldering reliability, making the devices suitable for industrial and power conversion systems.
These common-mode chokes support operating voltages of up to 48 VAC or 80 VDC and can handle continuous currents ranging from 20.3 A to 35 A at ambient temperatures up to +70°C without current derating. At higher temperatures, current capacity must be reduced to ensure long-term reliability.
To deliver efficient performance, the EP21 series combines MnZn ferrite cores with flat-wire windings, providing high inductance values from 160 µH to 640 µH while keeping DC resistance as low as 0.44 mΩ. This design minimizes power losses, improves converter efficiency, and offers consistent EMI filtering with approximately 200 nH of stray inductance for reliable operation in high-frequency power applications.
The EP21 series delivers its highest impedance between 500 kHz and 3 MHz, depending on the model, making it highly effective at suppressing common-mode noise generated by high-frequency switching power converters and similar electronic circuits. This helps improve electromagnetic compatibility (EMC) and reduces unwanted electrical interference in power systems.
Designed mainly for DC-DC converters and other low-voltage EMC filtering applications, the EP21 common-mode chokes combine high current handling, low DC resistance, high inductance, and a compact surface-mount design. Their underbody terminal structure also helps reduce PCB space requirements, allowing engineers to enhance EMI performance while creating smaller and more efficient power electronics and industrial systems.
