## Technical Overview of SD18-3R3-R The **SD18-3R3-R** is a high-performance, low-profile power inductor manufactured by **Eaton (formerly Cooper Bussmann/Coiltronics)**. It is part of the SD series, designed specifically for applications where space is limited and high efficiency is required. --- ### 1. Key Technical Specifications | Parameter | Value | | :--- | :--- | | **Inductance** | 3.3 µH | | **Tolerance** | ±20% | | **DC Resistance (DCR)** | 0.0388 Ω (Typical) | | **Saturation Current ($I_{sat}$)** | 2.51 A | | **RMS Current ($I_{rms}$)** | 2.14 A | | **Shielding** | Magnetic Shielded | | **Operating Temperature** | -40°C to +125°C | --- ### 2. Physical Characteristics The SD18 series is known for its compact surface-mount design. * **Dimensions:** Approximately 5.2mm x 5.2mm. * **Height:** 1.8mm maximum (low profile). * **Construction:** Ferrite core material which provides a closed magnetic path to minimize Electromagnetic Interference (EMI). * **Termination:** Lead-free (RoHS compliant) matte tin over copper. --- ### 3. Functional Breakdown #### Magnetic Shielding Because it is **shielded**, the magnetic flux is contained within the inductor body. This prevents the component from interfering with nearby sensitive components on the PCB, which is critical in dense smartphone or wearable electronics. #### Saturation Current ($I_{sat}$) This value (2.51 A) represents the point where the inductance drops by a specified percentage (usually 30%). In the SD18-3R3-R, the core is designed for a "soft" saturation characteristic, meaning it doesn't lose performance abruptly when the current spikes. #### Low DCR The low Direct Current Resistance (38.8 mΩ) ensures that power loss due to heat ($P = I^2R$) is kept to a minimum, extending battery life in portable devices. --- ### 4. Common Applications * **DC-DC Converters:** Used as an energy storage element in buck, boost, or buck-boost regulators. * **Portable Electronics:** Ideal for mobile phones, digital cameras, and tablets due to the 1.8mm height. * **Computer Peripherals:** Used in local card voltage regulation. * **LED Drivers:** Providing stable current for backlighting systems. ---