## FST8140: Common Cathode Schottky Rectifier The **FST8140** is a high-power power Schottky rectifier designed for use in low voltage, high-frequency inverters, free-wheeling diodes, and polarity protection applications. It is typically housed in a rugged **TO-249 (or similar high-power)** package to handle significant current levels. --- ### 1. Key Technical Specifications | Parameter | Symbol | Value | | :--- | :--- | :--- | | **Maximum Repetitive Peak Reverse Voltage** | $V_{RRM}$ | 40 V | | **Average Forward Current** | $I_{F(AV)}$ | 80 A | | **Peak Forward Surge Current** | $I_{FSM}$ | 800 A | | **Maximum Forward Voltage Drop** (at 40A) | $V_F$ | ~0.65 V | | **Operating Junction Temperature** | $T_j$ | -55 to +150 °C | | **Configuration** | - | Common Cathode | --- ### 2. Internal Configuration The FST8140 is a **dual-diode** component. It consists of two Schottky diodes sharing a single cathode (the metal base/tab), while the two anodes are accessible via separate terminals. * **Pin 1:** Anode 1 * **Pin 2:** Anode 2 * **Center/Case:** Common Cathode --- ### 3. Features and Advantages * **Low Forward Voltage:** Because it is a Schottky diode, it has a lower $V_F$ than standard silicon diodes, leading to higher efficiency and less heat generation. * **High Speed Switching:** It features negligible reverse recovery time ($t_{rr}$), making it ideal for high-frequency power supplies. * **High Surge Capacity:** Capable of handling up to 800 Amps for short durations (8.3ms half sine wave). * **Guard Ring Protection:** Most versions include a guard ring for stress protection and long-term reliability. --- ### 4. Common Applications 1. **Switching Power Supplies (SMPS):** Used in the output rectification stage. 2. **Battery Chargers:** Provides polarity protection and high-efficiency charging. 3. **Solar Panel Bypass:** Prevents reverse current flow in solar arrays. 4. **Converters:** DC-to-DC converters where low power loss is critical. ---