2SA970 PNP Audio Amplifier Transistor To-92

2SA970 PNP Audio Amplifier Transistor TO-92 is a renowned small-signal transistor specifically designed for use in high-fidelity audio preamplification and low-noise circuit stages. Consequently, audio engineers highly favor this PNP silicon epitaxial device for its exceptionally low noise figure and high current gain linearity (h_FE), which are critical for maintaining signal integrity in sensitive audio paths. Housed in the widely recognized TO-92 package, the 2SA970 offers excellent performance for both voltage and current amplification tasks in the mid-frequency range. Furthermore, its complementary nature to the 2SC2240 NPN transistor makes it an essential component for building balanced, low-distortion differential input stages in vintage and modern amplifiers. Therefore, select the 2SA970 when your design demands minimal noise and superior clarity in audio reproduction.

Key Features:

• Low Noise Figure (NF): Exhibits extremely low noise characteristics, which is vital for use in the first amplification stages of high-gain audio circuits.
• High DC Current Gain (h_FE): Features a high gain value, typically classified in groups (R, O, Y) to facilitate precise matching for differential pairs.
• High Voltage Rating: Possesses a high collector-emitter breakdown voltage (V_CEO) of 120 V, providing ample margin for high-headroom designs.
• Complementary Pair: Serves as the PNP complement to the 2SC2240 NPN transistor, enabling the construction of balanced push-pull and differential stages.
• Small Signal Performance: Offers excellent linear performance at low currents, making it perfect for driving subsequent amplifier stages.

Technical Specifications:

• Transistor Type: PNP Silicon Epitaxial Transistor
• Collector-Base Voltage (V_CBO): 120 V
• Collector-Emitter Voltage (V_CEO): 120 V
• Emitter-Base Voltage (V_EBO): 5 V
• Collector Current (I_C) Max: 100 mA
• Collector Dissipation (P_C) Max: 500 mW
• Operating Junction Temperature (T_j): ≤ 150°C
• Noise Figure (NF): Typically 0.5 dB (at f = 1 kHz)
• DC Current Gain (h_FE): 40 to 400 (Group dependent)

Mechanical Specifications:

• Package Type: TO-92 (Plastic molded package)
• Mounting Style: Through-Hole Technology (THT)
• Lead Material: Tinned Copper
• Weight: ≈ 0.2 g

Dimensions:

• Body Height: ≈ 5.2 mm
• Body Diameter: ≈ 4.8 mm
• Lead Pitch: 1.27 mm (Standard for TO-92 pinout)
• Lead Length: ≈ 14 mm (Can be formed for various mounting requirements)

Pinout and Wiring:

• Pin 1 (Emitter – E): Connects to the common reference or ground, often the output terminal in common-collector configuration.
• Pin 2 (Collector – C): Connects to the voltage supply rail via a load (e.g., resistor or transformer primary).
• Pin 3 (Base – B): Receives the small input signal, controlling the current flow between the emitter and collector.
• Note: The pin assignment, when viewing the flat face, is typically Emitter, Collector, Base (E-C-B), consequently, always confirm this arrangement with the specific manufacturer’s datasheet.

Datasheet Reference:

• Download 2SA970 Transistor Datasheet

Commonly Used in:

• Phono Preamplifiers (Phono Stages): Its low noise figure makes it highly effective in amplifying the minute signals from moving magnet cartridges.
• Mixing Consoles: Used within input stages of professional audio mixers to maintain signal clarity before equalization.
• DIY Audio Amplifiers: A popular choice for hobbyists and audiophiles building headphone amps and high-end preamps.

Applications:

• Low-Noise Preamplification: Amplifies small signals from microphones or passive sources with minimal added hiss or interference.
• Voltage Regulators: Functions as a high-gain driver in precision linear voltage regulation circuits.
• Differential Amplifier Pairs: Forms the core input stage of operational amplifiers and power amplifier stages, significantly reducing common-mode distortion.

Equivalent Models:

• KSA970 (ON Semiconductor): A direct and highly popular equivalent, however, verify the specific h_FE grade for matching purposes.
• 2SA1313: Another small-signal PNP transistor often used as an alternative, but check the noise characteristics against the 2SA970 requirements.
• BC559: A general-purpose PNP with lower voltage ratings; in fact, it can replace the 2SA970 in non-critical, low-voltage applications.

Package Includes:

• 1 x 2SA970 PNP Audio Amplifier Transistor TO-92