The **CMS2-1-R** is a high-performance **Common Mode Choke** (Surface Mount Device) manufactured by Coiltronics (a brand of Eaton). It is primarily designed for EMI (Electromagnetic Interference) suppression in power and signal lines. --- ## 1. Technical Specifications The following table summarizes the key electronic characteristics of the CMS2-1-R: | Feature | Specification | | :--- | :--- | | **Inductance (Typical)** | 11.2 µH | | **Current Rating (RMS)** | 2.5 Amps | | **DCR (DC Resistance)** | 0.038 Ω (Max) | | **Mounting Type** | Surface Mount (SMD) | | **Dimensions** | ~ 9.4mm x 7.0mm x 5.0mm | | **Operating Temperature** | -40°C to +125°C | --- ## 2. Key Electronic Functions ### A. Common Mode Noise Suppression The primary purpose of the CMS2-1-R is to filter out common-mode noise—interference that travels in the same direction on both signal lines. Because the magnetic fields from the two windings cancel each other out for differential signals but add up for common-mode noise, it provides high impedance to noise without affecting the intended signal. ### B. High Current Capability Despite its small footprint, the "CMS2" series is designed to handle relatively high RMS currents (up to 2.5A for this specific model), making it suitable for DC-DC converters and small power supply units. ### C. Toroidal Core Construction The part utilizes a toroidal (ring-shaped) ferrite core. This geometry is highly efficient because it contains the magnetic flux within the core, resulting in very low electromagnetic radiation (EMI) to surrounding components. --- ## 3. Common Applications * **DC-DC Converters:** Filtering input/output stages to meet EMC regulations. * **Power Supplies:** Used in switching power supplies to reduce high-frequency ripple. * **Data Lines:** Protecting high-speed data transmission from external interference. * **Industrial Electronics:** Ensuring signal integrity in noisy electrical environments. --- ## 4. Materials and Compliance * **Lead-Free:** Compliant with RoHS standards. * **Termination:** Matte Tin over Copper plating for excellent solderability. * **Packaging:** Available in Tape and Reel for automated pick-and-place assembly.