## CTX20-4A-R: Component Analysis The **CTX20-4A-R** is a high-performance **surface-mount power inductor** (specifically a dual-winding transformer/inductor) manufactured by Eaton (formerly Coiltronics). It belongs to the **OCTA-PAC® PLUS** series, designed for high power density and versatile configurations. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Inductance (L)** | 19.8 µH (Series) / 4.95 µH (Parallel) | | **Rated Current (Irms)** | 1.81 A (Series) / 3.62 A (Parallel) | | **DC Resistance (DCR)** | 0.081 Ω (Max) | | **Mounting Type** | Surface Mount (SMD) | | **Operating Temp** | -40°C to +125°C | | **Material** | Iron Powder Core | | **Construction** | Dual-winding (Two separate coils) | --- ### 2. Functional Characteristics The "4A" designation indicates high-power handling capabilities, and the "R" suffix confirms **RoHS compliance**. * **Dual Winding Design:** It contains two identical windings that can be connected in series or parallel. This allows a single component to serve multiple circuit roles. * **High Power Density:** Optimized for high-frequency applications where space is limited but power output is high. * **Low EMI:** The toroidal shape of the core naturally helps contain magnetic flux, reducing electromagnetic interference with surrounding components. --- ### 3. Common Applications This part is primarily used in power conversion circuits: 1. **DC-DC Converters:** Used in Buck, Boost, and SEPIC topologies. 2. **Buck-Boost Transformers:** Can act as a 1:1 transformer for voltage isolation or level shifting. 3. **Input/Output Filters:** Excellent for smoothing current ripples in switching power supplies. 4. **Common Mode Chokes:** When wired appropriately, it can filter out high-frequency noise in signal lines. --- ### 4. Configuration Diagram Because it has two windings, the behavior changes based on how the pins are bridged: ```text Parallel Connection: Series Connection: (Pins 1-4 and 2-3) (Pin 2 to Pin 3) 1 o----┐ 1 o-------) | ) 2 o----┘ 2 o---┐ ) | ) 3 o----┐ 3 o---┘ ) | ) 4 o----┘ 4 o-------) ```