The **CMS1-4-R** is a specific model of a **Common Mode Inductor (Choke)** manufactured by **Coiltronics** (a brand under Eaton/Bussmann). It belongs to the CMS series, which is designed for noise suppression in power electronics and signal lines. --- ## 1. Technical Specifications The following table outlines the key electrical and physical characteristics of the CMS1-4-R: | Feature | Specification | | :--- | :--- | | **Inductance (Typical)** | 213 µH | | **Current Rating (Irms)** | 1.1 Amps | | **DCR (Direct Current Resistance)** | 0.117 Ω (Max per winding) | | **Number of Windings** | 2 (Dual) | | **Mounting Type** | Surface Mount (SMT) | | **Package/Case** | Vertical or Horizontal Toroidal Mount | | **Operating Temperature** | -40°C to +155°C | --- ## 2. Core Functional Parts The CMS1-4-R is composed of three primary electronic elements: ### A. Ferrite Core The device utilizes a high-permeability ferrite toroid core. This core is engineered to provide high impedance at specific frequency ranges to "choke" or block high-frequency electromagnetic interference (EMI) while allowing DC and low-frequency signals to pass. ### B. Dual Windings The part contains two separate copper wire windings. In a standard application: * **Common Mode:** Current flows in the same direction through both windings, creating a combined magnetic field that is resisted by the core's inductance. * **Differential Mode:** Current flows in opposite directions, causing the magnetic fields to cancel out, allowing the signal to pass with minimal impedance. ### C. Termination/Base The "R" in the part number indicates it is **RoHS compliant**. The leads are finished with tin over copper, ensuring reliable solder joints for surface mount technology (SMT) assembly. --- ## 3. Key Applications Because of its small footprint and high-temperature rating, the CMS1-4-R is commonly used in: 1. **Switch Mode Power Supplies (SMPS):** To filter out switching noise. 2. **DC-DC Converters:** To reduce ripple current and EMI. 3. **Data Lines:** Protecting sensitive communication lines from external noise. 4. **Industrial Electronics:** Due to the wide operating temperature range (-40°C to +155°C). --- ## 4. Part Number Breakdown * **CMS:** Series Name (Common Mode Surface Mount). * **1:** Size code (refers to the physical dimensions of the toroid/base). * **4:** Number of turns/inductance variation within that size class. * **R:** RoHS Compliant.