350 V AC X2 Capacitors for EMI Suppression

TDK Corporation has introduced the B3292xU/V series of X2 safety film capacitors rated at 350 V (AC), designed for interference suppression in industrial and automotive systems connected in series with the mains. The components address space constraints in applications such as on-board chargers, EV charging systems, PV inverters, energy meters, and capacitive power supplies.

Extended Voltage and Capacitance Range
The new series supports capacitance values from 47 nF to 1.8 µF in compact lead spacings of 15 mm and 22.5 mm. Across the full portfolio, lead spacings range from 15 mm to 52.5 mm, with capacitance coverage up to 20 µF.

Rated at 350 V (AC), the capacitors withstand peak voltage pulses up to 2.5 kV in accordance with IEC 60384-14, the applicable standard for safety capacitors used in electromagnetic interference (EMI) suppression. These X2-class capacitors are intended for “across-the-line” configurations, where they mitigate differential-mode noise directly at the AC input.

For developers of industrial drives and automotive power converters, the higher AC voltage rating compared to standard 275 V (AC) X2 capacitors enables additional design headroom in fluctuating mains environments.

Environmental Robustness and Automotive Qualification
The B3292xU/V series passed the THB (temperature, humidity, bias) test at +85 °C, 85% relative humidity, and rated voltage for 1,000 hours, meeting Grade III, Test Condition B requirements. This qualification indicates stable electrical performance under combined thermal and moisture stress, a critical factor for outdoor EV charging systems and PV inverters.

The capacitors are compliant with AEC-Q200, the automotive standard for passive component reliability. They are specified for maximum operating temperatures up to +110 °C and feature self-healing metallized film technology, which isolates dielectric breakdown sites to maintain functionality after transient overvoltage events.

In addition, the components are tested at a DC voltage of 1,505 V for 2 seconds, supporting insulation robustness verification during production.

Application Context in Power Electronics
In systems such as on-board chargers and industrial motor drives, EMI suppression capacitors play a key role in meeting conducted emission limits defined by international standards. As switching frequencies increase to improve efficiency and power density, interference mitigation becomes more challenging within limited PCB space.

By combining compact dimensions with extended voltage capability, the B3292xU/V series addresses the need for space-optimized EMI suppression in next-generation converters. The availability of design tools and SPICE models further supports integration into simulation-driven development workflows.

Competitive Context
Within the X2 capacitor class defined by IEC 60384-14, key benchmarks include AC voltage rating, peak pulse withstand capability, THB endurance, and automotive qualification. The 350 V (AC) rating and 2.5 kV pulse capability position the series above standard 275 V (AC) X2 components typically used in general-purpose mains filtering, offering higher margin for industrial and automotive environments with unstable line conditions.

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