The **SDQ25-681-R** is a high-performance, dual-winding shielded surface mount (SMD) inductor manufactured by **Eaton (formerly Cooper Bussmann)**. It belongs to the SDQ series, known for its versatility in power conversion applications. --- ## 1. Technical Specifications The following table summarizes the core electrical and physical characteristics of the SDQ25-681-R: | Parameter | Specification | | :--- | :--- | | **Inductance** | 680 µH | | **Tolerance** | ±20% | | **DC Resistance (DCR)** | ~1.58 Ω (Typical) | | **Rated Current (Irms)** | 0.358 Amps | | **Saturation Current (Isat)** | 0.380 Amps | | **Configuration** | Dual Winding (4 Terminals) | | **Shielding** | Magnetically Shielded | | **Dimensions** | 5.2mm x 5.2mm x 2.5mm | --- ## 2. Key Electronic Features ### Dual Winding Versatility The most significant feature of this part is the **two separate windings** on a single core. This allows the component to function in multiple ways depending on how it is wired to the PCB: * **Series Connection:** Increases the total inductance. * **Parallel Connection:** Increases the current handling capability. * **Transformer Mode:** Can act as a 1:1 ratio transformer for isolation or SEPIC converters. ### Magnetic Shielding The "SDQ" series features a ferrite drum and sleeve construction. This provides **magnetic shielding**, which is critical for: * Minimizing Electromagnetic Interference (EMI). * Protecting sensitive nearby components from the inductor's magnetic field. * Reducing audible noise in power circuits. ### Low Profile Design With a height of only **2.5mm**, it is ideal for "tight-fit" electronics like smartphones, tablets, and thin DC-DC converter modules. --- ## 3. Typical Applications The SDQ25-681-R is commonly found in the following electronic circuits: 1. **SEPIC Converters:** (Single-Ended Primary-Inductor Converters) where two inductors are required on a single core to maintain high efficiency. 2. **Buck/Boost Regulators:** Used for voltage regulation in battery-powered devices. 3. **Common Mode Chokes:** To filter out high-frequency noise in power lines. 4. **LED Drivers:** Providing stable current for high-intensity lighting. --- ## 4. Part Number Breakdown Understanding the nomenclature helps in identifying variants: * **SDQ:** Series name (Shielded Dual Winding). * **25:** Size code (approx. 5.2mm x 2.5mm). * **681:** Inductance code ($68 \times 10^1$ = 680 µH). * **R:** RoHS compliant.