The **CMT1-3-R** is a high-performance, surface-mount (SMT) common mode choke manufactured by **Coiltronics (now a brand of Eaton)**. It is primarily designed to suppress electromagnetic interference (EMI) and noise in power supply and data line applications. --- ## 1. Technical Specifications The CMT1-3-R belongs to the CMT series, known for high current capacity and compact footprints. | Parameter | Value / Specification | | :--- | :--- | | **Inductance** | 3.0 mH (Typical) | | **Rated Current** | ~1.6 Amps | | **DCR (Direct Current Resistance)** | ~0.160 Ohms (Maximum) | | **Mounting Type** | Surface Mount (SMD/SMT) | | **Package/Case** | CMT1 Horizontal/Low Profile | | **Operating Temperature** | -40°C to +125°C | --- ## 2. Key Electronic Features ### A. Core Material and Construction * **Toroidal Core:** It utilizes a ferrite toroid core which offers high efficiency and low magnetic radiation (stray flux), preventing interference with adjacent components. * **Dual Winding:** The device consists of two identical coils wound on a single core. These coils are phased to cancel out common-mode noise while allowing differential-mode signals to pass. ### B. Common Mode Suppression The primary electronic function is to provide **high impedance** to common-mode currents (noise flowing in the same direction on both lines) while providing **low impedance** to the intended differential-mode current (the power/signal). ### C. Environmental Compliance * **RoHS Compliant:** The "-R" suffix in the part number indicates that the component is lead-free and meets RoHS standards. * **Thermal Stability:** Rated for industrial temperature ranges, making it suitable for automotive and industrial power modules. --- ## 3. Typical Applications The CMT1-3-R is commonly integrated into the following circuits: 1. **Switch Mode Power Supplies (SMPS):** Used in the input filter stage to prevent switching noise from feeding back into the AC line. 2. **DC-DC Converters:** Suppresses high-frequency noise generated by high-speed switching transistors. 3. **Solar Inverters:** Filters EMI in renewable energy power conversion systems. 4. **EV Charging:** Used in onboard chargers for electric vehicles to maintain electromagnetic compatibility (EMC). --- ## 4. Part Number Breakdown | Segment | Meaning | | :--- | :--- | | **CMT** | Series Name (Common Mode Toroid) | | **1** | Size/Body Dimension Code | | **3** | Inductance Identifier (3.0 mH) | | **-R** | RoHS Compliant |