## FST40180: Schottky Barrier Rectifier The **FST40180** is a high-power Schottky Barrier Diode (Rectifier) typically used in industrial power supplies and high-frequency applications. It is designed for high efficiency due to its low forward voltage drop. --- ### 1. Key Technical Specifications Below are the primary electrical characteristics for a standard FST40180 device: | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | **Max Recurrent Peak Reverse Voltage** | $V_{RRM}$ | 180 | Volts (V) | | **Max Average Forward Current** | $I_{F(AV)}$ | 40 | Amperes (A) | | **Max Peak Forward Surge Current** | $I_{FSM}$ | 400 - 600 | Amperes (A) | | **Max Forward Voltage Drop** ($I_F = 20A$) | $V_F$ | ~0.80 - 0.90 | Volts (V) | | **Operating Junction Temperature** | $T_j$ | -55 to +150 | °C | --- ### 2. Physical and Internal Construction * **Package Type:** Usually comes in a **TO-249** or a specialized **SMD/Power Module** package (like the MiniMod). * **Configuration:** It is often a **Dual Diode** (Common Cathode or Common Anode), meaning there are two diodes inside a single package, each rated for half the total current (e.g., 2 x 20A = 40A). * **Material:** Silicon Schottky technology, which utilizes a metal-to-semiconductor junction rather than a P-N junction. --- ### 3. Features & Benefits 1. **Low Switching Losses:** Being a Schottky diode, it has zero reverse recovery time ($t_{rr}$), making it ideal for high-speed switching. 2. **High Thermal Conductivity:** The packaging is designed to be mounted directly to a heatsink to manage the 40A current load. 3. **Guard Ring Protection:** Most versions include a guard ring for transient protection and improved long-term reliability. --- ### 4. Common Applications The FST40180 is frequently found in: * **Switch Mode Power Supplies (SMPS):** Used on the secondary (output) side for rectification. * **Battery Chargers:** Preventing back-flow and handling high charging currents. * **Free Wheeling Diodes:** Used in motor control circuits to protect against inductive spikes. * **Solar Inverters:** Used in string combiners or DC-DC conversion stages. --- ### 5. Identification Schematic A typical internal schematic for a Common Cathode version: ```text Anode 1 (Pin 1) ----|>|----| |---- Cathode (Base/Case) Anode 2 (Pin 2) ----|>|----| ```