The **W2CE-111-R** is a specific surface-mount (SMT) common mode choke manufactured by **Wurth Elektronik** (WE). It belongs to the **WE-CNSW** series and is primarily designed for high-speed data line filtering. ### 1. Technical Specifications Below is a breakdown of the key electrical and physical parameters of the W2CE-111-R: | Parameter | Value | | :--- | :--- | | **Impedance (@ 100 MHz)** | 110 $\Omega$ | | **Rated Current** | 400 mA | | **DC Resistance (max)** | 0.30 $\Omega$ | | **Rated Voltage** | 50 V (DC) | | **Insulation Test Voltage** | 125 V (DC) | | **Operating Temperature** | -40 °C to +125 °C | | **Package Size** | 0805 (Metric 2012) | --- ### 2. Internal Construction The device consists of two coils wound around a single ferrite core. * **Common Mode Suppression:** It allows differential signals (the data) to pass through with minimal attenuation while providing high impedance to common-mode noise (interference affecting both lines). * **Core Material:** Ferrite, optimized for high-frequency noise suppression. * **Terminations:** Matte Tin (Sn) plating over Nickel (Ni) for excellent solderability. --- ### 3. Key Applications Because of its small footprint and 110 $\Omega$ impedance profile, it is commonly used in the following interfaces: 1. **USB 2.0 / 3.0:** Filtering noise on data lines without distorting the high-speed signal. 2. **IEEE 1394 (Firewire):** Maintaining signal integrity in communications. 3. **LVDS (Low Voltage Differential Signaling):** Used in display panels and high-speed backplanes. 4. **CAN Bus:** Suppressing electromagnetic interference (EMI) in automotive or industrial networking. --- ### 4. Circuit Diagram Representation In a schematic, the W2CE-111-R is represented as two coupled inductors with dots indicating the polarity (phasing) of the windings: ```text Line 1 In o----( Coil 1 )----o Line 1 Out ) ( Line 2 In o----( Coil 2 )----o Line 2 Out ``` ---