## Overview of SDQ25-8R2-R The **SDQ25-8R2-R** is a high-performance, surface-mount (SMD) dual-winding inductor, commonly known as a **Coupled Inductor**. It is manufactured by Eaton (formerly Bussmann/Coiltronics) as part of the SDQ series. These components are unique because they consist of two separate coils wound on a single ferrite core, allowing them to be used as inductors, transformers, or for common-mode filtering. --- ### Technical Specifications | Parameter | Value / Description | | :--- | :--- | | **Inductance** | 8.2 µH (Nominal) | | **Tolerance** | ±20% | | **Current Rating (Irms)** | ~2.01 Amps | | **Saturation Current (Isat)** | ~2.54 Amps | | **DC Resistance (DCR)** | ~0.0632 Ω (Max) | | **Mounting Type** | Surface Mount (SMD) | | **Dimensions** | 5.2mm x 5.2mm x 2.5mm | | **Number of Windings** | 2 (Dual Winding) | | **Core Material** | Ferrite | --- ### Key Electronic Features 1. **Dual Winding Versatility:** * **Series Connection:** If the two coils are connected in series, the total inductance increases (approx. $4 \times L$). * **Parallel Connection:** If connected in parallel, the inductance remains the same as a single coil, but the current-carrying capacity doubles. 2. **Magnetic Shielding:** The SDQ series is magnetically shielded, which minimizes Electromagnetic Interference (EMI) and prevents the magnetic field from affecting nearby components on the PCB. 3. **High Power Density:** Its compact 5.2mm footprint allows for high current handling in a small vertical profile (2.5mm height), making it ideal for space-constrained mobile or industrial electronics. 4. **1:1 Turns Ratio:** Since both windings have an equal number of turns, it is frequently used as a 1:1 isolation transformer or a SEPIC inductor. --- ### Common Applications * **SEPIC Converters:** Used in Single-Ended Primary-Inductor Converters where two inductors are required to maintain a constant output voltage regardless of whether the input is higher or lower than the output. * **Buck/Boost Converters:** Used as a coupled inductor to improve efficiency and reduce ripple. * **Common Mode Chokes:** Used to filter out high-frequency noise in power lines. * **Transformers:** Can function as 1:1 isolation or flyback transformers for low-power applications. --- ### Comparison: Series vs. Parallel Wiring When integrating the SDQ25-8R2-R into a circuit, the wiring configuration significantly changes its behavior: | Configuration | Inductance | Current Rating | | :--- | :--- | :--- | | **Parallel** | 8.2 µH | Higher Current (Double) | | **Series** | 32.8 µH | Standard Current | ---