The **SD20-221-R** is a specific part number for a surface-mount power inductor manufactured by **Eaton (formerly Cooper Bussmann)**. It belongs to the SD20 series, which is characterized by its low profile and high power density. --- ### 1. Key Technical Specifications The part number encodes specific data about the component's performance. Here is the breakdown: | Parameter | Value | Description | | :--- | :--- | :--- | | **Inductance** | 220 µH | The nominal inductance value. | | **Tolerance** | ±20% | Standard deviation allowed from nominal value. | | **DC Resistance (DCR)** | ~1.36 Ω | The internal resistance of the copper winding. | | **Isat (Saturation Current)** | ~0.33 A | The current at which inductance drops by 30%. | | **Irms (RMS Current)** | ~0.46 A | The current that causes a 40°C temperature rise. | | **Package Size** | 5.2 x 5.2 x 2.0 mm | Compact square footprint for PCB mounting. | --- ### 2. Part Number Breakdown The nomenclature `SD20-221-R` can be decoded as follows: * **SD:** Product family (Shielded Drum Inductor). * **20:** Size code (refers to the 2.0mm height). * **221:** Inductance code. The first two digits (22) are the value, and the third (1) is the multiplier (10^1). Thus, 22 x 10 = 220 µH. * **-R:** RoHS compliant (Lead-free). --- ### 3. Physical & Material Features * **Magnetic Shielding:** The inductor is magnetically shielded. This is crucial for high-density boards as it prevents electromagnetic interference (EMI) from affecting nearby sensitive components. * **Construction:** It utilizes a ferrite drum core with a ferrite sleeve, providing a closed magnetic path. * **Mounting:** Designed for **SMT (Surface Mount Technology)** with high-temperature solder reflow compatibility. --- ### 4. Common Applications Due to its high inductance (220 µH) and compact size, it is typically found in: 1. **DC-DC Converters:** Used as energy storage elements in buck, boost, or SEPIC converters. 2. **LED Drivers:** Providing stable current for lighting circuits. 3. **Battery Powered Devices:** Ideal for laptops, handheld instruments, and IoT sensors where vertical space (2.0mm) is limited. 4. **Filtering:** Used in LC filters to smooth out ripple voltage in power supplies. ---