## ESD-R-38B: Ferrite Core for EMI Suppression The **ESD-R-38B** is a high-performance **Ferrite Core** (specifically a round cable suppression core) manufactured by KEMET. It is designed to mitigate electromagnetic interference (EMI) in electronic circuits by absorbing high-frequency noise. --- ### 1. Technical Specifications The following table outlines the physical and magnetic characteristics of the ESD-R-38B. | Parameter | Specification | | :--- | :--- | | **Material** | Manganese-Zinc (Mn-Zn) | | **Outer Diameter (OD)** | 38.0 mm | | **Inner Diameter (ID)** | 19.0 mm | | **Height (H)** | 13.0 mm | | **Weight** | 50.0 g (approx.) | | **Operating Temperature** | -25°C to +85°C | | **Frequency Range** | High frequency (AM band to MHz range) | --- ### 2. Electronic Functionality The ESD-R-38B functions as a **passive low-pass filter**. When a cable is looped through the core, it introduces impedance to the line without affecting the signal data or power flow (DC or low-frequency AC). * **Noise Absorption:** It converts high-frequency electromagnetic noise into a negligible amount of heat. * **Common Mode Choke:** When used on a pair of wires (or a whole cable bundle), it suppresses common-mode currents that cause electromagnetic radiation. * **Impedance vs. Frequency:** As the frequency of the noise increases, the impedance ($Z$) of the ferrite core increases, effectively blocking the interference. --- ### 3. Key Applications Because of its size and material composition, the ESD-R-38B is commonly used in industrial and consumer electronics: 1. **Consumer Electronics:** Power cords for TVs, audio equipment, and computers to prevent flickering or static. 2. **Industrial Machinery:** Protecting control signals from the noise generated by motors or high-power switching power supplies. 3. **Medical Equipment:** Ensuring sensitive diagnostic tools are not affected by ambient radio frequency interference (RFI). 4. **Office Equipment:** Copiers, printers, and scanners. --- ### 4. Implementation Example To maximize the effectiveness of the ESD-R-38B, the cable should be passed through the center. Multiple turns can be used to increase impedance. ```text Impedance Calculation Tip: Z (Total) = Z (Single Turn) × (Number of Turns)² ``` ---