## SD18-2R2-R Electronic Component Overview The **SD18-2R2-R** is a high-power density, low-profile power inductor manufactured by **Eaton (formerly Cooper Bussmann)**. It belongs to the SD series of surface-mount (SMD) inductors. ### 1. Key Specifications The following table highlights the primary electrical and physical characteristics: | Parameter | Specification | | :--- | :--- | | **Inductance** | 2.2 µH | | **Tolerance** | ±20% | | **DC Resistance (DCR)** | 0.0323 Ω (Max) | | **Rated Current (Irms)** | 2.58 A | | **Saturation Current (Isat)** | 3.32 A | | **Shielding** | Shielded (Magnetic) | | **Operating Temperature** | -40°C to +125°C | | **Package / Case** | 5.20mm x 5.20mm x 1.80mm | --- ### 2. Physical Construction and Design The "SD18" designation refers to the physical dimensions of the part: * **Form Factor:** Square footprint (approx. 5.2mm) with a very low height (1.8mm), making it ideal for space-constrained electronics. * **Shielding:** It features a ferrite drum core with a ferrite sleeve (shielded). This minimizes electromagnetic interference (EMI) with surrounding components. * **Material:** The core is made of Ferrite, which provides high efficiency and low core losses at high frequencies. ### 3. Part Number Breakdown The nomenclature can be decoded as follows: 1. **SD:** Series name (Shielded Drum). 2. **18:** Size code (refers to the 1.8mm height). 3. **2R2:** Inductance value (2.2 microhenries). The 'R' acts as a decimal point. 4. **R:** RoHS compliant / Lead-free. --- ### 4. Typical Applications Because of its small size and high current capability, the SD18-2R2-R is commonly found in: * **DC-DC Converters:** Used in buck, boost, and SEPIC topologies. * **Mobile Devices:** Smartphones, tablets, and handheld GPS units. * **Computer Peripherals:** Hard drives and SSDs. * **Battery Powered Equipment:** Where high efficiency is required to extend battery life. --- ### 5. Technical Considerations When integrating this part into a circuit, consider the following: * **Self-Resonant Frequency (SRF):** Ensure the switching frequency of your power supply is well below the SRF of the inductor. * **Saturation:** The `Isat` value (3.32A) is the point where inductance drops by 30%. Designing too close to this limit can lead to efficiency loss and overheating. * **Thermal Management:** The `Irms` value (2.58A) is based on a temperature rise of approximately 40°C. High ambient temperatures may require current derating.