The **SD25-470-R** is a high-performance, low-profile, shielded drum core inductor manufactured by **Eaton (formerly Cooper Bussmann/Coiltronics)**. It is part of the SD25 series, widely used in power management circuits where space is limited and electromagnetic interference (EMI) must be minimized. --- ### 1. Key Technical Specifications The part number "SD25-470-R" encodes specific technical data: | Parameter | Value / Description | | :--- | :--- | | **Inductance** | 47.0 µH | | **Tolerance** | ±20% | | **DC Resistance (DCR)** | 0.287 Ω (Typical) | | **Rated Current (Irms)** | 0.88 Amps (Temperature rise base) | | **Saturation Current (Isat)** | 0.84 Amps (Inductance drop base) | | **Shielding** | Ferrite Drum Core (Magnetic Shielding) | | **Configuration** | Surface Mount (SMD) | --- ### 2. Physical Characteristics * **Dimensions:** Approximately 5.2mm x 5.2mm with a height of 2.5mm. * **Construction:** It features a ferrite core with a metallic shield around the windings. This design traps the magnetic flux, preventing it from interfering with nearby components. * **Packaging:** Supplied on Tape and Reel (indicated by the "-R" suffix) for automated SMT assembly. --- ### 3. Core Functions & Applications The SD25-470-R is primarily used as an energy storage or filtering element in the following scenarios: #### Common Use Cases: * **DC-DC Converters:** Used in Buck (step-down), Boost (step-up), and SEPIC topologies. * **Filtering:** Acts as a low-pass filter to smooth out ripple current in power supplies. * **Portable Electronics:** Ideal for smartphones, tablets, and wearables due to its low profile (2.5mm). * **Noise Suppression:** The magnetic shielding makes it suitable for EMI-sensitive environments like RF modules or sensor interfaces. --- ### 4. Circuit Symbol and Implementation In a schematic, it is represented by the standard inductor symbol. Below is a conceptual example of its placement in a switching regulator: ```mermaid graph LR Vin(Input Voltage) --> Inductor[SD25-470-R] Inductor --> Vout(Smooth Output) Switching_IC -- Controls --> Inductor ``` --- ### 5. Selection Considerations When designing with the SD25-470-R, engineers must consider: 1. **Saturation:** If the current exceeds 0.84A, the inductance will drop significantly, potentially causing the circuit to fail or overheat. 2. **Thermal Management:** The Irms rating (0.88A) indicates the current at which the part will heat up by approximately 40°C above ambient temperature. 3. **Footprint Compatibility:** Ensure the PCB pads match the 5.2mm square footprint.