## FDV0840-R42M: Electronic Component Overview The **FDV0840-R42M** is a high-current, shielded surface-mount (SMD) power inductor manufactured by Murata (specifically from the TOKO heritage line). It is designed for high-efficiency DC-DC conversion applications. ### 1. Technical Specifications The part number follows a specific nomenclature that defines its physical and electrical characteristics. | Parameter | Specification | | :--- | :--- | | **Inductance** | 0.42 µH | | **Tolerance** | ±20% | | **DC Resistance (DCR)** | ~1.6 mΩ (Max) | | **Isat (Saturation Current)** | ~21.2 A (based on 30% drop in L) | | **Irms (Rated Current)** | ~18.8 A (based on 40°C temp rise) | | **Dimensions (LxWxH)** | 8.4 x 8.0 x 4.0 mm | | **Operating Temp** | -40°C to +125°C | --- ### 2. Key Internal Components & Materials * **Magnetic Core:** Utilizes a metal alloy powder core. Unlike traditional ferrite, metal powder cores offer "soft" saturation characteristics, meaning the inductance drops gradually rather than abruptly as current increases. * **Winding:** Features a heavy-gauge copper wire to minimize DC resistance (DCR), which reduces heat dissipation and improves efficiency. * **Shielding:** The component is magnetically shielded. The core material surrounds the winding, minimizing Electromagnetic Interference (EMI) with surrounding components on the PCB. --- ### 3. Application Use Cases This specific inductor is found in power management stages where high current and low profile are required: 1. **Voltage Regulator Modules (VRMs):** Used in CPU/GPU power delivery for servers and laptops. 2. **Point of Load (PoL) Converters:** High-efficiency step-down (Buck) converters. 3. **Battery Powered Devices:** Due to low DCR, it helps extend battery life by reducing power loss during conversion. --- ### 4. Part Number Breakdown * **FDV:** Series name (Metal alloy, shielded). * **0840:** Dimensions (8.0mm width x 4.0mm height). * **R42:** Inductance value (R = decimal point; 0.42 µH). * **M:** Tolerance (M = ±20%).