## ESD-R-38SR: Toroidal Ferrite Core for EMI Suppression The **ESD-R-38SR** is a high-performance toroidal ferrite core manufactured by KEMET. It is specifically designed for EMI (Electromagnetic Interference) suppression in round cables. These components are essential for ensuring electromagnetic compatibility (EMC) by filtering out high-frequency noise. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Material** | Manganese-Zinc (MnZn) | | **Shape** | Toroidal (Ring) | | **Outer Diameter (A)** | 38.0 mm | | **Inner Diameter (B)** | 19.0 mm | | **Height (C)** | 13.0 mm | | **Operating Temperature** | -25°C to +85°C | | **Primary Application** | Noise suppression in the MHz range | --- ### 2. Functional Overview The ESD-R-38SR works by increasing the **impedance** of a conductor at high frequencies without affecting the low-frequency signals or DC power. * **Inductive Reactance:** When a cable is looped through the core, the ferrite material concentrates the magnetic field, creating an inductor. * **Lossy Characteristics:** At high frequencies, the material becomes "lossy," converting EMI energy into a tiny amount of heat rather than allowing it to radiate as interference. --- ### 3. Usage & Implementation #### Mounting Methods * **Single Pass:** The cable simply passes through the center. * **Multiple Turns:** For increased impedance (efficiency), the cable can be wrapped through the hole multiple times. The impedance increases approximately by the square of the number of turns ($Z \propto N^2$). #### Common Applications 1. **Industrial Equipment:** Protecting sensitive control circuits from motor noise. 2. **Consumer Electronics:** Reducing noise in power cords and data cables. 3. **Power Supplies:** Filtering switching noise at the output stages. 4. **Medical Devices:** Ensuring high signal integrity in diagnostic equipment. --- ### 4. Advantages of the "SR" Series The "SR" suffix typically denotes specific material characteristics optimized for high-frequency performance or specific coating types. In the KEMET catalog, this series is favored for: * **High Permeability:** Effective at lower frequency ranges compared to Nickel-Zinc (NiZn) cores. * **Reliability:** Stable performance across the rated temperature range. * **Ease of Retrofit:** Can be added to existing cable designs without redesigning the PCB.