IN Brief:
- WE-SLSP common-mode chokes use a four-terminal 5050 SMT package measuring 2.5mm high.
- The range covers 100–2,000Ω impedance at 100MHz, with rated currents from 1.3A to 6A.
- Intended applications include industrial PLC connections, 24–48V buses, 48V PoE, and microinverters.
Würth Elektronik has introduced the WE-SLSP series of common-mode chokes, combining current ratings of up to 6A with a package height of 2.5mm for electronic connections requiring electromagnetic interference suppression.
The surface-mount components are designed for signal and data lines that may also carry electrical power. Würth Elektronik has specified a rated voltage of 100V, low leakage inductance, and several impedance options to accommodate different filtering requirements.
WE-SLSP devices use a four-terminal 5050 SMT package. The available variants cover common-mode impedance values from 100Ω to 2,000Ω at 100MHz, with rated currents between 1.3A and 6A and DC resistance values from 15mΩ to 73mΩ.
The combination is intended for circuit designs where the electrical connection must carry relatively high operating current without allowing unwanted high-frequency interference to propagate through external wiring. Package height is another constraint, particularly in compact controllers and assemblies with limited space above the PCB.
Common-mode interference consists of unwanted currents travelling in the same direction through conductors that normally carry a differential signal or electrical supply. These currents can be coupled into the circuit by switching devices, nearby electronics, or the surrounding electromagnetic environment.
A common-mode choke uses coupled windings to introduce impedance to currents that flow in the same direction. In normal differential operation, the magnetic fields generated by opposing currents largely cancel, allowing the intended signal or supply current to pass with relatively little added inductive impedance.
The cancellation is not perfect. Winding geometry, coupling, magnetic material, and parasitic effects determine the residual differential impedance and the choke’s behaviour over frequency.
Würth Elektronik identifies low leakage inductance as one of the WE-SLSP series’ characteristics. That is important where the filtered connection carries data because excessive differential impedance can distort the signal or change its electrical behaviour.
Common-mode impedance is frequency-dependent, and the specified value at 100MHz provides only one point on the component’s performance curve. The actual attenuation obtained in a circuit depends on the interference spectrum, source and load impedances, PCB design, and connected cabling.
Six current ratings and impedance options are not interchangeable without considering the complete operating conditions. Selecting a higher-impedance component may provide more opposition to a particular interference frequency, but its resistance, current capability, and effect on the intended signal must also be considered.
DC resistance is especially relevant where power is transferred through the filtered connection. Resistive dissipation increases with the square of operating current, so internal heating can become significant as current rises.
The rated current therefore needs to be assessed together with temperature rise and the component’s thermal environment. A current rating does not establish that the component can operate indefinitely at that current under every enclosure temperature and PCB layout.
Würth Elektronik identifies programmable logic controller connections and industrial bus systems operating between 24V and 48V as applications. The series is also suitable for consideration in telecommunications equipment using 48V Power over Ethernet and in electronic assemblies associated with renewable energy microinverters.
These applications share a need to control conducted electromagnetic interference while maintaining the electrical characteristics of the connection. A PLC installation, for example, may contain multiple switching loads and control interfaces within the same cabinet, creating several possible paths for interference to enter communications wiring.
Microinverters create a different electrical environment, with high-frequency power conversion occurring close to sensing, control, and communication circuitry. The relevant filtering requirements depend on where the component is installed and which conductors carry the unwanted common-mode current.
Power over Ethernet combines data communication and electrical power delivery through the connected cable infrastructure. Filter selection must account for the intended interface characteristics as well as the current that the relevant conductors are expected to carry.
The low-profile WE-SLSP package gives PCB designers another option when a larger common-mode choke would be difficult to accommodate. Its four-terminal configuration also allows integration into surface-mount assembly processes without requiring a separate through-hole component.
Component selection nevertheless remains a circuit-level exercise. Signal integrity measurements, conducted emissions testing, and appropriate immunity testing are needed to establish how the finished equipment behaves with the choke installed.
Würth Elektronik says all versions of the new series are available from stock, with free samples offered for evaluation and no minimum order value. The availability of different impedance and current configurations allows comparative testing before a final PCB design is released.
The WE-SLSP range provides compact common-mode filtering options for electrical connections carrying both power and data. Its suitability for a particular design will depend on measured interference performance, thermal conditions, and the electrical requirements of the connected interface.
