The **CTX100-4-R** is a high-performance, surface-mount (SMT) power inductor belonging to the **OCTA-PAC® PLUS** series, originally manufactured by Cooper Bussmann (now part of **Eaton**). It is unique because it features **dual windings**, allowing it to be configured as a single inductor, a coupled inductor, or a 1:1 transformer. --- ## 1. Key Technical Specifications The specifications of the CTX100-4-R depend on how the two internal windings are connected (Series vs. Parallel). | Parameter | Parallel Connection | Series Connection | | :--- | :--- | :--- | | **Inductance (L)** | 100.2 µH | 400.8 µH | | **DC Resistance (DCR)** | 0.232 Ω (Typ) | 0.928 Ω (Typ) | | **I-rms (Heating Current)** | 1.34 A | 0.67 A | | **I-sat (Saturation Current)** | 1.12 A | 0.56 A | ### General Characteristics: * **Part Number Suffix (-R):** Indicates RoHS compliance. * **Size Code (-4):** Refers to the physical dimensions of the core/enclosure. * **Core Material:** Powder Iron (high saturation flux density). * **Operating Temperature:** -40°C to +125°C. --- ## 2. Structural Design The CTX100-4-R is designed with two identical windings on a single toroid core, housed in a molded, surface-mount package. * **Versatility:** It has four leads. By jumping the pins on the PCB, the user chooses the circuit behavior. * **Shielding:** The toroidal geometry inherently provides low EMI (Electro-Magnetic Interference) compared to open-core inductors. * **Ruggedness:** The "PLUS" designation indicates higher power density and better thermal management than the standard OCTA-PAC series. --- ## 3. Common Applications Because of its dual-winding nature, it is frequently used in the following electronic circuits: 1. **DC-DC Converters:** Used as a standard buck or boost inductor. 2. **SEPIC Converters:** Acts as the coupled inductor required to maintain energy flow between the input and output stages. 3. **1:1 Transformers:** Ideal for isolation or creating a negative voltage rail from a positive input (Inverting Flyback). 4. **Common Mode Choke:** Used in EMI filtering to suppress noise on power lines. --- ## 4. Selection Considerations * **Saturation:** Ensure the peak current in your application does not exceed the **I-sat** rating, or the inductance will drop sharply. * **Footprint:** It is a relatively large SMT component. Ensure the PCB layout accounts for the specific OCTA-PAC 4 dimensions (approx. 15mm x 13mm). * **Thermal Management:** The **I-rms** rating is based on a 40°C temperature rise. In enclosed or high-ambient environments, derating may be necessary.