The **2SA1531A-R** is a high-frequency, low-noise PNP epitaxial silicon transistor. It is primarily designed for use in the low-noise amplifier stages of audio equipment and high-fidelity pre-amplifiers. --- ### 1. Key Technical Specifications The following table summarizes the absolute maximum ratings and electrical characteristics for the 2SA1531A-R: | Parameter | Symbol | Rating | Unit | | :--- | :--- | :--- | :--- | | **Collector-Base Voltage** | $V_{CBO}$ | -150 | V | | **Collector-Emitter Voltage** | $V_{CEO}$ | -150 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | -5 | V | | **Collector Current (DC)** | $I_C$ | -50 | mA | | **Collector Power Dissipation** | $P_C$ | 300 | mW | | **Junction Temperature** | $T_j$ | 150 | °C | | **DC Current Gain (hFE)** | $h_{FE}$ | 180 to 390 | (R Rank) | --- ### 2. The "R" Classification The suffix **"R"** in the part number refers specifically to the **hFE (Current Gain) Rank**. Transistors in this series are binned based on their gain levels: * **Rank R:** 180 – 390 * **Rank S:** 270 – 560 * **Rank T:** 400 – 800 Selecting the "R" rank ensures a specific range of amplification, which is critical for maintaining balance in stereo audio circuits. --- ### 3. Features & Applications #### Features * **Low Noise Figure:** Specifically engineered to have a low noise floor, making it ideal for processing weak signals. * **High Voltage:** With a $V_{CEO}$ of -150V, it can handle high-voltage swings in professional audio gear. * **High Linearity:** Provides clean amplification with minimal distortion. #### Common Applications 1. **Phono Pre-amplifiers:** Amplifying the low-level signal from turntable cartridges. 2. **Microphone Amplifiers:** Used in the initial input stages of mixers. 3. **Hifi Audio:** Voltage amplification stages in integrated amplifiers. --- ### 4. Complementary Part In push-pull circuit designs or differential pairs, the 2SA1531A-R (PNP) is often paired with its NPN counterpart: * **Complementary NPN:** **2SC3944A** --- ### 5. Package Information The device typically comes in a **TO-92** or a similar small-signal plastic package, which is suitable for through-hole PCB mounting.