The **SD18-221-R** is a high-performance, low-profile, shielded drum core inductor manufactured by **Eaton (formerly Cooper Bussmann/Coiltronics)**. It is part of the SD18 series, designed for compact electronic applications requiring efficient power conversion. --- ### 1. Technical Specifications The following table outlines the primary electrical and physical characteristics of the SD18-221-R: | Parameter | Specification | | :--- | :--- | | **Inductance** | 220 µH | | **Tolerance** | ±20% | | **Rated Current (Irms)** | 0.35 Amps (350 mA) | | **Saturation Current (Isat)** | 0.40 Amps (400 mA) | | **DC Resistance (DCR)** | 1.348 Ohms (Typ.) | | **Operating Temperature** | -40°C to +125°C | | **Package / Case** | 5.2mm x 5.2mm x 1.8mm | | **Mounting Type** | Surface Mount (SMD) | --- ### 2. Key Features * **Magnetic Shielding:** The component is magnetically shielded, which minimizes Electromagnetic Interference (EMI) and prevents the magnetic field from affecting neighboring components on the PCB. * **Low Profile:** With a maximum height of 1.8mm, it is ideal for height-constrained devices like smartphones, tablets, and thin wearables. * **Ferrite Core Construction:** Provides high permeability and low core losses at high frequencies. * **RoHS Compliant:** The "-R" suffix indicates that the part is lead-free and meets RoHS environmental standards. --- ### 3. Common Applications The SD18-221-R is typically used in power management circuits, including: 1. **DC-DC Converters:** Buck (step-down), Boost (step-up), and SEPIC topologies. 2. **LED Drivers:** Providing stable current for backlighting or lighting modules. 3. **Portable Electronics:** Used in digital cameras, GPS units, and handheld medical devices. 4. **Noise Filtering:** Acts as a low-pass filter to smooth out ripples in power supply lines. --- ### 4. Part Number Breakdown ```text SD 18 - 221 - R | | | | | | | └── RoHS Compliant | | └─────── Inductance Value: 22 (first two digits) + 1 (multiplier) = 220µH | └──────────── Size Code: (approx. 5.2mm x 1.8mm) └──────────────── Series Name: Shielded Drum Core ```