The **MPSA42L-AB3-R** is a high-voltage NPN epitaxial silicon transistor designed for applications requiring high breakdown voltages. It is commonly used in video output stages, gas discharge displays, and high-voltage switching circuits. --- ## 1. Technical Specifications The following table summarizes the key electrical characteristics of the MPSA42L-AB3-R: | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | **Collector-Base Voltage** | $V_{CBO}$ | 300 | V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 300 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | 6.0 | V | | **Collector Current (DC)** | $I_C$ | 500 | mA | | **Power Dissipation ($T_a = 25^\circ C$)** | $P_D$ | 625 | mW | | **DC Current Gain** | $h_{FE}$ | 40 - 200 | - | | **Transition Frequency** | $f_T$ | 50 | MHz | --- ## 2. Part Number Breakdown Understanding the suffix and prefix of the **MPSA42L-AB3-R**: * **MPSA42**: The base part number for a high-voltage NPN transistor. * **L**: Often indicates "Lead-Free" or specific low-power/low-noise characteristics depending on the manufacturer (UTC - Unisonic Technologies). * **AB3**: Refers to the **SOT-89** package type (a small, surface-mount plastic package). * **R**: Indicates the packing method, typically **Tape & Reel**. --- ## 3. Key Applications Because of its high $V_{CEO}$ rating of 300V, this part is utilized in specialized environments: * **Telecommunication:** Used in line interface circuits and electronic telephone ringers. * **Display Drivers:** Driving Nixie tubes, neon lamps, or high-voltage gas discharge displays. * **Power Supplies:** Low-power high-voltage regulation and switching. * **Video:** CRT video output stages (though less common in modern flat panels). --- ## 4. Pinout Configuration (SOT-89) When looking at the top of the SOT-89 package (pins pointing down): 1. **Pin 1:** Base (B) 2. **Pin 2:** Collector (C) - *Also connected to the large center tab for heat dissipation.* 3. **Pin 3:** Emitter (E) ---