The **LD1-270-R** is a high-current, surface-mount (SMT) power inductor manufactured by Eaton (formerly Cooper Bussmann/Coiltronics). It is part of the LD series, designed for high density and efficiency in power conversion circuits. --- ### 1. Key Technical Specifications The following table highlights the primary electrical and physical characteristics of the LD1-270-R: | Feature | Specification | | :--- | :--- | | **Inductance** | 27.0 µH | | **Tolerance** | ±20% | | **Rated Current (Irms)** | ~1.14 Amps (typical) | | **Saturation Current (Isat)** | ~1.10 Amps (typical) | | **DC Resistance (DCR)** | ~0.198 Ohms (max) | | **Operating Temperature** | -40°C to +125°C | | **Package Type** | Surface Mount (SMT) | --- ### 2. Physical Construction The "LD" designation refers to the **Low Profile Drum Core** construction. * **Core Material:** Ferrite. This ensures high efficiency and low core losses at high frequencies. * **Shielding:** This specific series is generally **unshielded**. While this makes the part more cost-effective and provides a higher saturation current for its size, it requires careful PCB placement to avoid EMI (Electromagnetic Interference) with sensitive nearby components. * **Terminations:** Matte tin over copper, providing excellent solderability for reflow processes. --- ### 3. Part Number Breakdown The nomenclature for the LD series follows a specific logic: * **LD1:** Refers to the physical size/dimension of the inductor (Size 1). * **270:** Represents the inductance value in microhenries (µH). The first two digits are significant figures, and the third is the multiplier (10^0). Thus, $27 \times 1 = 27$ µH. * **-R:** Indicates that the part is **RoHS compliant**. --- ### 4. Common Applications Due to its balance of size and current handling, the LD1-270-R is commonly found in: 1. **DC-DC Converters:** Used as energy storage elements in buck, boost, or SEPIC converters. 2. **LED Drivers:** Providing constant current for lighting applications. 3. **Battery Powered Devices:** Ideal for handheld electronics due to the low-profile design. 4. **Filter Networks:** Used for noise suppression in power supply lines. --- ### 5. Design Considerations * **Self-Resonant Frequency (SRF):** Ensure the operating frequency of your circuit is well below the SRF to maintain inductive behavior. * **Thermal Management:** The $I_{rms}$ rating is based on a specific temperature rise (usually 40°C). If the ambient temperature is high, derating may be necessary. * **Magnetic Flux:** Since it is unshielded, avoid placing sensitive high-impedance traces directly underneath the inductor.