### Overview of CTX20-3P-R The **CTX20-3P-R** is a high-performance, surface-mount (SMT) power inductor belonging to the **OCTA-PAC®** series manufactured by **Eaton (formerly Bussmann/Coiltronics)**. This component is unique because it features **dual windings**, allowing it to be configured as a single inductor, a coupled inductor, or a 1:1 transformer. --- ### Key Specifications The following table outlines the primary electrical and physical characteristics of the CTX20-3P-R: | Parameter | Specification | | :--- | :--- | | **Inductance (Parallel)** | 20.32 µH | | **Inductance (Series)** | 81.28 µH | | **Current Rating (Isat)** | ~2.5 A (configuration dependent) | | **DC Resistance (DCR)** | ~0.054 Ω (Parallel) | | **Operating Temperature** | -40°C to +125°C | | **Package Type** | SMT (Surface Mount) | | **Size / Dimension** | ~11.43mm x 11.43mm | | **RoHS Status** | Compliant (-R suffix) | --- ### Detailed Part Breakdown 1. **Dual Winding Design:** The device consists of two identical windings wound on a single toroidal core. This provides high magnetic coupling between the two coils. 2. **Configurability:** * **Series Connection:** Increases total inductance (L total = L1 + L2 + 2M). * **Parallel Connection:** Increases current handling capacity while maintaining the base inductance. * **Transformer Mode:** Can be used as a 1:1 isolation transformer or for SEPIC (Single-Ended Primary-Inductor Converter) topologies. 3. **Core Material:** It typically utilizes a **powdered iron core**, which offers excellent energy storage capabilities and a "soft" saturation characteristic, meaning the inductance drops gradually as current increases rather than crashing abruptly. 4. **Applications:** * **DC-DC Converters:** Buck, Boost, and Forward converters. * **SEPIC Converters:** Ideal due to the coupled windings. * **Noise Filtering:** Used as a common-mode choke to filter electromagnetic interference (EMI). * **Isolation:** Providing signal or power isolation in low-power circuits. --- ### Schematic Symbol & Layout When designing a PCB for the CTX20-3P-R, it is treated as a 4-terminal device: * **Terminals 1 & 4:** First Winding (Start/Finish) * **Terminals 2 & 3:** Second Winding (Start/Finish) ---