The **SD25-331-R** is a specific model of power inductor manufactured by **Eaton (formerly Bussmann)**. It belongs to the **SD25 series**, which is characterized by its shielded drum core construction and low profile. --- ### 1. General Specifications The part number "SD25-331-R" can be broken down to understand its primary characteristics: | Parameter | Value | Description | | :--- | :--- | :--- | | **Series** | SD25 | Shielded Drum, 5.2mm x 5.2mm footprint | | **Inductance** | 330 µH | The nominal inductance (331 = 33 + one zero) | | **Tolerance** | ±20% | Standard industry tolerance for power inductors | | **RoHS** | -R | Suffix indicating lead-free/RoHS compliance | --- ### 2. Technical Performance This component is designed for high-density power applications. Below are the typical electrical ratings for this specific part: * **Inductance:** 330 Microhenries (µH) * **DC Resistance (DCR):** Approximately 2.45 Ohms (Ω) — This is the internal resistance of the copper wire. * **Rated Current (Irms):** ~0.33 Amperes — The current at which the temperature rises by 40°C. * **Saturation Current (Isat):** ~0.35 Amperes — The current at which the inductance drops by 30%. * **Operating Temperature:** -40°C to +125°C. --- ### 3. Key Physical Features The SD25 series is favored in modern electronics for several reasons: * **Magnetic Shielding:** The ferrite drum core is wrapped in a magnetic shield. This minimizes **Electromagnetic Interference (EMI)**, ensuring it doesn't interfere with nearby sensitive components. * **Low Profile:** With a height of roughly 2.5mm, it is ideal for thin consumer electronics. * **Surface Mount (SMD):** Designed for automated PCB assembly processes. --- ### 4. Common Applications Due to its high inductance (330µH) and moderate current handling, the SD25-331-R is typically used in: 1. **DC-DC Converters:** Buck, Boost, and SEPIC topologies. 2. **LED Drivers:** Providing steady current for lighting circuits. 3. **Battery Powered Devices:** Mobile phones, digital cameras, and handheld sensors. 4. **Filtering:** Used as a low-pass filter to remove noise from power supply lines. ---