The **MMBT3906-AE3-R** is a widely used Surface Mount Device (SMD) version of the classic 2N3906 general-purpose PNP transistor. It is designed for small-signal amplification and switching applications. --- ### 1. Technical Specifications The following table summarizes the key electrical characteristics of the MMBT3906-AE3-R: | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | **Transistor Type** | Type | PNP | - | | **Collector-Emitter Voltage** | $V_{CEO}$ | -40 | V | | **Collector-Base Voltage** | $V_{CBO}$ | -40 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | -5.0 | V | | **Collector Current (DC)** | $I_C$ | -200 | mA | | **Power Dissipation** | $P_D$ | 350 | mW | | **DC Current Gain** | $h_{FE}$ | 100 - 300 | (@ $I_C$ = -10mA) | | **Transition Frequency** | $f_T$ | 250 | MHz | --- ### 2. Package and Pinout Details The "AE3" suffix typically refers to the **SOT-23** package, which is a standard 3-pin small outline transistor package used in high-density PCB designs. #### Pin Configuration: 1. **Base (B):** Controls the current flow between the emitter and collector. 2. **Emitter (E):** The source of charge carriers (holes for PNP). 3. **Collector (C):** Receives the charge carriers. --- ### 3. Key Features and Applications The MMBT3906 is the complementary PNP pair to the **MMBT3904** (NPN). Using them together allows for "Push-Pull" circuit designs. #### Common Uses: * **Switching:** Used to turn small loads (LEDs, relays) on or off. In PNP transistors, the load is typically connected between the collector and ground, and it turns "ON" when the base is pulled low. * **Amplification:** Used in low-noise pre-amplifier stages for audio or sensor signals. * **Signal Processing:** High-speed switching (up to 250 MHz) makes it suitable for pulse-width modulation (PWM) and logic gate buffers. --- ### 4. Part Number Breakdown The suffixing follows specific manufacturer naming conventions (often UTC or similar): * **MMBT3906:** The core part number (PNP Small Signal Transistor). * **AE3:** Indicates the **SOT-23** package type. * **R:** Usually indicates **Tape & Reel** packaging for automated pick-and-place assembly.