The **SD20-220-R** is a high-density, shielded surface-mount (SMD) power inductor manufactured by **Eaton (formerly Coiltronics / Bussmann)**. It belongs to the SD20 series, which is widely used in power management applications due to its compact size and low magnetic radiation. Here is a detailed breakdown of the electronic characteristics, specifications, and applications of the SD20-220-R. --- ## 1. Part Number Breakdown Understanding the nomenclature helps identify the component's core attributes: | Part Component | Meaning | Description | | :--- | :--- | :--- | | **SD** | Series Name | Shielded Drum Core Inductor | | **20** | Size Code | Dimensions (approx. 5.2 mm x 5.2 mm x 2.0 mm) | | **220** | Inductance Value | $22 \times 10^0 = 22\ \mu\text{H}$ (Microhenries) | | **-R** | Compliance | RoHS Compliant / Lead-Free | --- ## 2. Key Technical Specifications The SD20-220-R is engineered for efficiency in DC-DC converters. Below are its primary electrical and physical parameters: ### Electrical Properties * **Nominal Inductance:** $22\ \mu\text{H}$ * **Tolerance:** $\pm 20\%$ * **Direct Current Resistance (DCR):** * Typical: $0.243\ \Omega$ (243 mΩ) * Maximum: $0.292\ \Omega$ (292 mΩ) * **Rated Current ($I_{rms}$):** ~0.96 A (Current that causes a $40^\circ\text{C}$ temperature rise) * **Saturation Current ($I_{sat}$):** ~0.84 A (Current that causes inductance to drop by 30%) ### Physical & Environmental Properties * **Shielding:** Ferrite core (Magnetic shielding minimizes Electromagnetic Interference - EMI) * **Operating Temperature Range:** $-40^\circ\text{C}$ to $+125^\circ\text{C}$ (Includes self-heating) * **Package Size:** 5.2mm width x 5.2mm length x 2.0mm height --- ## 3. Core Functions and Working Principle The SD20-220-R operates primarily as an energy storage device. 1. **Energy Storage:** During the "ON" state of a switching regulator, current flows through the inductor, storing energy in its magnetic field. 2. **Filtering:** It works in tandem with capacitors to smooth out switching ripples, converting a choppy square-wave input into a smooth DC output. 3. **EMI Suppression:** Because it is **magnetically shielded**, the magnetic flux lines are contained within the ferrite housing. This prevents the inductor from interfering with nearby sensitive components on the PCB. --- ## 4. Typical Applications This inductor is ideal for low-profile, space-constrained applications requiring high efficiency: * **DC-DC Converters:** Buck (step-down), Boost (step-up), and SEPIC topologies. * **Consumer Electronics:** Digital cameras, handheld gaming consoles, and GPS units. * **Computing:** Power supplies for microprocessors, flash memory, and local-area network (LAN) cards. * **Battery-Powered Devices:** Cell phones and IoT sensors where low DCR is critical to preserving battery life. --- ## 5. Typical Application Circuit (Example) In a standard Buck Converter circuit, the SD20-220-R ($L_1$) is placed between the switching node and the output load. ```text Input Voltage (Vin) ---> [ Switching Regulator / IC ] | v (Switch Node) +----[ SD20-220-R (22uH) ]----+---> Output Voltage (Vout) | [ Capacitor ] | GND ```