## Technical Overview of SD3112-8R2-R The **SD3112-8R2-R** is a low-profile, shielded surface-mount (SMD) power inductor. It is part of the SD3112 series manufactured by **Eaton (formerly Coiltronics/Bussmann)**. These inductors are specifically designed for applications where space is constrained and electromagnetic interference (EMI) must be minimized. --- ### 1. Key Specifications The following table highlights the primary electrical and physical characteristics: | Parameter | Value | | :--- | :--- | | **Inductance** | 8.2 µH | | **Tolerance** | ±20% | | **DC Resistance (DCR)** | 0.380 Ω (380 mΩ) Typical | | **Saturation Current ($I_{sat}$)** | 0.62 A | | **RMS Current ($I_{rms}$)** | 0.73 A | | **Shielding** | Magnetically Shielded | | **Package Size** | 3.1mm x 3.1mm x 1.2mm | | **Operating Temperature** | -40°C to +125°C | --- ### 2. Core Components and Design The SD3112-8R2-R consists of three main electronic/structural parts: * **Ferrite Drum Core:** The central part around which the wire is wound. Ferrite is used for its high magnetic permeability and low electrical conductivity, reducing eddy current losses. * **Copper Winding:** A precision-wound copper wire that creates the magnetic field. The thickness and number of turns determine the 8.2 µH inductance and the DCR. * **Magnetic Shield (Ring Core):** A ferrite sleeve or coating that surrounds the winding. This "closes" the magnetic loop, which serves two purposes: 1. **EMI Reduction:** It prevents the magnetic field from interfering with neighboring components. 2. **Efficiency:** It focuses the magnetic flux within the inductor. --- ### 3. Application Use Cases Because of its small footprint (3.1mm footprint and only 1.2mm height), this part is commonly found in: * **DC-DC Converters:** Used as energy storage elements in buck, boost, or SEPIC converters. * **Mobile Electronics:** Smartphones, tablets, and wearables where board height is critical. * **LED Drivers:** Providing stable current for backlighting or indicator LEDs. * **Noise Filtering:** Acting as a low-pass filter in power supply lines to remove high-frequency ripple. --- ### 4. Part Number Breakdown Understanding the nomenclature helps in identifying variants: `SD` `31` `12` - `8R2` - `R` * **SD:** Series name (Shielded Drum). * **31:** Dimensions (approx. 3.1mm width/length). * **12:** Height (approx. 1.2mm). * **8R2:** Inductance value ($8.2$ µH). The 'R' acts as a decimal point. * **R:** RoHS compliant / Green material. ---