## Analysis of CMT4-5-R (Common Mode Choke) The **CMT4-5-R** is a high-performance, through-hole **Common Mode Choke** manufactured by Eaton (formerly Bussmann/Coiltronics). It is primarily designed to suppress electromagnetic interference (EMI) and noise in power supply applications. --- ### 1. Technical Specifications The following table highlights the key electrical and physical characteristics of the CMT4-5-R: | Parameter | Specification | | :--- | :--- | | **Inductance** | 15.0 mH (Minimum) | | **Rated Current** | 1.8 Amps | | **DC Resistance (DCR)** | 0.180 Ohms (Max per winding) | | **Voltage Rating** | 250 VAC | | **Dielectric Strength** | 1500 VAC (Winding to Winding) | | **Operating Temperature** | -40°C to +125°C | | **Mounting Type** | Through-Hole (Vertical Mount) | --- ### 2. Functional Role in Electronics Common mode chokes like the CMT4-5-R are used to filter out noise that is common to two or more lines (usually the "Line" and "Neutral" of an AC power source). * **Noise Suppression:** It provides high impedance against high-frequency noise while allowing the desired low-frequency power currents to pass with minimal resistance. * **Safety & Compliance:** It helps electronic devices meet EMI/RFI standards (such as FCC or CISPR) by preventing electrical noise from leaking back into the power grid. * **Dual Winding:** It consists of two identical coils wound on a single toroidal core. The magnetic fields produced by the differential (useful) currents cancel out, while the magnetic fields for common-mode (noise) currents add up, providing the filtering effect. --- ### 3. Physical Configuration and Pinout The "4" in the series usually refers to the physical size/frame, and the "R" indicates that the part is **RoHS Compliant**. ```text Pin Configuration (Typical): [1] ○-------( )-------○ [4] (Winding A) Core [2] ○-------( )-------○ [3] (Winding B) * Pin 1 & 2 are usually Input * Pin 3 & 4 are usually Output ``` --- ### 4. Common Applications * **Switch Mode Power Supplies (SMPS):** Used in the input stage to clean incoming AC power. * **Industrial Electronics:** Protecting sensitive sensors from motor drive noise. * **Consumer Appliances:** Used in washing machines, refrigerators, and chargers. * **Telecommunications:** Filtering DC power lines in base stations. ---