## SDQ25-680-R: Dual Winding Inductor Analysis The **SDQ25-680-R** is a high-performance, shielded dual-winding inductor (transformer) manufactured by **Eaton (formerly Bussmann/Coiltronics)**. It is part of the SDQ25 series, known for its versatility in power conversion applications. --- ### 1. Key Technical Specifications The "680" in the part number indicates the inductance value, while the "R" signifies RoHS compliance. | Parameter | Specification | | :--- | :--- | | **Inductance (Parallel)** | 67.5 µH (±20%) | | **Inductance (Series)** | 270.2 µH (±20%) | | **Current Rating (Irms)** | ~0.82 A (Parallel) | | **Peak Current (Isat)** | ~0.87 A (Parallel) | | **DC Resistance (DCR)** | 0.441 Ω (Typical per winding) | | **Operating Temperature** | -40°C to +125°C | | **Package Size** | 5.2mm x 5.2mm x 2.5mm | --- ### 2. Physical Construction & Features * **Dual Winding:** It consists of two separate coils wound on a single ferrite core. This allows the component to be used as an inductor, a 1:1 transformer, or a common-mode choke. * **Shielded Design:** The magnetic shielding minimizes Electromagnetic Interference (EMI), making it suitable for noise-sensitive environments. * **Surface Mount (SMT):** Designed for automated pick-and-place assembly. * **Coupling Coefficient:** Features high coupling between the two windings (typically >0.98). --- ### 3. Electronic Functionality & Configurations Because it has two independent windings, the SDQ25-680-R can be wired in three primary ways: 1. **Parallel Mode:** Connects the two windings in parallel. This doubles the current capacity while keeping the base inductance (68µH). 2. **Series Mode:** Connects the two windings in series. This quadruples the inductance ($L_{total} = L_1 + L_2 + 2M$) to approximately 270µH. 3. **Transformer Mode:** Uses one winding as the primary and the other as the secondary. This is common in **SEPIC**, **ZETA**, and **Flyback** converters for 1:1 voltage transformation or isolation. --- ### 4. Typical Applications * **DC-DC Converters:** Specifically Buck, Boost, and SEPIC topologies. * **Battery Powered Devices:** Due to its small footprint and high efficiency. * **Input/Output Filters:** Used as a common-mode choke to filter electrical noise. * **LED Drivers:** Providing stable current regulation in compact lighting modules. --- ### 5. Identification Code Breakdown `SDQ` `25` - `680` - `R` * **SDQ:** Series Name (Shielded Dual Winding). * **25:** Size code (approx. 2.5mm height). * **680:** Inductance code (68 followed by 0 zeros = 68 µH). * **R:** RoHS compliant.