The **LF2020BNP-R523** is a high-performance **Common Mode Choke** (AC Line Filter) manufactured by **Sumida**. It is primarily used in power supply circuits to suppress electromagnetic interference (EMI) and noise. --- ## 1. Technical Specifications Below is a breakdown of the key electrical and physical characteristics for this specific part: | Parameter | Specification | | :--- | :--- | | **Inductance (Min)** | 5.2 mH | | **Rated Current** | 2.0 A (Approx.) | | **DC Resistance (Max)** | 0.16 Ω | | **Voltage Rating** | 250 VAC | | **Operating Temperature** | -40°C to +105°C | | **Mounting Type** | Through-Hole (Vertical) | | **Core Material** | Ferrite | --- ## 2. Key Features * **High Impedance:** Designed to provide high impedance at low frequencies to effectively filter out common-mode noise. * **Compact Design:** The "2020" series signifies a compact footprint, making it suitable for high-density PCB layouts. * **Reliability:** Uses high-quality ferrite cores and automated winding technology for consistent electrical performance. * **Safety Compliance:** Designed to meet standard safety requirements for AC line applications. --- ## 3. Circuit Application The LF2020BNP-R523 is typically placed at the **AC Input** stage of an electronic device. Its primary functions include: 1. **Noise Suppression:** Preventing high-frequency noise generated by the device's internal switching power supply (SMPS) from leaking back into the power grid. 2. **External Protection:** Protecting the sensitive internal electronics from noise coming from the external AC power line. ### Typical Use Cases: * Switching Power Supplies (SMPS) * LED Lighting Drivers * Home Appliances (Washing machines, Air conditioners) * Industrial Power Units --- ## 4. Internal Construction The device consists of two identical coils wound in opposite directions on a single ferrite core. * **Common Mode Signals:** When noise flows in the same direction on both lines, the magnetic fields add up, creating high impedance and blocking the noise. * **Differential Mode Signals:** The intended power current flows in opposite directions, causing the magnetic fields to cancel out, allowing the power to pass with minimal resistance.