The **CMS1-3-R** is a high-performance, surface-mount (SMT) common mode choke manufactured by **Eaton (formerly Coiltronics)**. It is part of the CMS series, specifically designed for noise suppression in power electronics and signal lines. --- ## 1. Technical Specifications The following table outlines the primary electrical and physical characteristics of the CMS1-3-R: | Parameter | Specification | | :--- | :--- | | **Inductance** | 218 µH (Typical) | | **Current Rating (Irms)** | 1.4 Amps | | **DCR (DC Resistance)** | 114 mΩ (Max per winding) | | **Voltage Rating** | 160 Vdc | | **Operating Temperature** | -40°C to +130°C | | **Package/Case** | Size 1 (Surface Mount) | | **Number of Windings** | 2 | --- ## 2. Key Features The CMS1-3-R is engineered with specific materials and structural choices to optimize performance in compact circuits: * **Toroidal Core Construction:** Uses a ferrite toroid core which provides high efficiency and low electromagnetic interference (EMI) by keeping the magnetic flux contained within the core. * **Dual Winding:** Consists of two identical windings. In common mode applications, the magnetic fields from the supply and return currents cancel each other out for the signal but add up for noise, providing high impedance to unwanted interference. * **Pick and Place Compatible:** Designed with a flat top for automated assembly lines. * **Lead-Free/RoHS Compliant:** The "-R" suffix indicates that the part is fully compliant with RoHS standards. --- ## 3. Common Applications This component is typically found in environments where high-frequency noise needs to be filtered without degrading the primary signal or power flow: 1. **Switch Mode Power Supplies (SMPS):** Used to filter out common mode noise generated by high-frequency switching transistors. 2. **DC-DC Converters:** Acts as an input or output filter to meet EMC (Electromagnetic Compatibility) regulations. 3. **Signal Lines:** Protects sensitive data lines from industrial interference. 4. **Telecommunications:** Used in power-over-ethernet (PoE) and high-speed data equipment. --- ## 4. Connection Diagram The device features four terminals. Depending on the PCB layout, it can be used for common mode or differential mode filtering: ```text Winding 1: Pins 1 --- 4 Winding 2: Pins 2 --- 3 Common Mode Setup: Line In -> Pin 1 | Line Out -> Pin 4 Return In -> Pin 2 | Return Out -> Pin 3 ``` ---