onsemi 2N3702

Overview

2N3702 from Fairchild Semiconductor is a PNP epitaxial silicon transistor designed for general-purpose amplification and switching in low-to-medium power circuits, with V_CEO = −25 V, I_C = −500 mA continuous, h_FE = 60–300 at −50 mA/−5 V, and TO-92 package. It operates across −55°C to +150°C and supports applications such as signal inversion in discrete logic stages and load switching in industrial control interfaces.

For engineers reviewing the 2N3702 datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, −25 V collector-emitter breakdown, −500 mA DC current capability, saturation voltages (V_CE(sat) = −0.25 V, V_BE(sat) = −0.6 to −1.0 V), and thermal resistance (R_θJA = 200 °C/W).

Technical Context

The 2N3702 is a medium-gain, medium-speed PNP bipolar junction transistor optimized for linear amplification and saturated switching. Its f_T of 100 MHz and C_ob of 12 pF indicate suitability for audio-frequency and low-RF analog gain stages, while its −500 mA I_C rating supports robust switching of relays or indicator LEDs without external buffering.

It features fixed three-terminal topology (Emitter–Collector–Base) in TO-92, with guaranteed BV_(BR)CEO ≥ −25 V and ICBO ≤ −100 nA, enabling stable operation in temperature-varying environments where leakage-sensitive bias networks are used.

Key Specifications

Pinout & Package

2N3702 is housed in a standard TO-92 plastic package with 3 leads. Lead identification (viewed from flat side, leads down): Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose transistor applications.

Compared with MPSA92 and BC557, the 2N3702 offers balanced trade-offs: moderate voltage rating (−25 V), robust current handling (−500 mA), and mid-range h_FE stability-making it ideal for cost-sensitive industrial controls where reliability across temperature and load variation is prioritized over extreme specs.

Availability

2N3702 is available at Aetrix Electronics and suitable for industrial sensor interfaces, discrete logic inverters, audio preamplifiers, and power supply sequencing control requiring stable component supply and long-term manufacturability.

Supply support for 2N3702 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based designer and manufacturer of analog and discrete semiconductors, acquired by ON Semiconductor in 2016; known for high-reliability bipolar transistors and power management ICs.

The 2N3702 belongs to Fairchild's legacy general-purpose bipolar transistor family, engineered for broad utility in analog signal conditioning, discrete logic, and medium-current switching across industrial, instrumentation, and consumer electronics.

FAQ

What is the maximum continuous collector current rating for the 2N3702?

The 2N3702 has a maximum continuous collector current (I_C) rating of −500 mA at T_A = 25°C. Derating applies above 25°C per the specified 5.0 mW/°C thermal coefficient. This rating supports driving moderate-power loads such as relays, LEDs, or small solenoids without external current boosting. Always verify junction temperature rise using R_θJA = 200 °C/W in actual layout conditions.

Does the 2N3702 have a documented h_FE range, and under what test conditions?

Yes, the 2N3702 specifies h_FE = 60–300 measured at V_CE = −5.0 V and I_C = −50 mA. This range reflects production variation across batches and ensures predictable base current requirements for both linear amplification and saturated switching. The minimum value allows conservative design of base drive resistors, while the maximum supports low-drive applications where base current must be minimized.

What are the absolute maximum voltage ratings for the 2N3702?

The 2N3702 absolute maximum voltage ratings are: V_CEO = −25 V, V_CBO = −40 V, and V_EBO = −5.0 V. These define the upper limits for reverse-biased junctions before irreversible damage occurs. Exceeding any of these-even momentarily-risks permanent degradation. Designers should apply ≥20% margin in safety-critical applications, especially where inductive kickback or supply transients are present.

Is the 2N3702 suitable for high-frequency amplifier applications?

The 2N3702 has an f_T of 100 MHz and C_ob of 12 pF, making it suitable for audio-frequency amplification (up to ~20 kHz) and low-RF applications such as IF buffers or oscillator followers. It is not recommended for RF power amplification or >10 MHz narrowband tuned circuits due to gain roll-off and parasitic limitations. For such uses, purpose-built RF transistors like the MRF901 should be selected instead of the 2N3702.

How is the pinout oriented on the 2N3702 TO-92 package?

When viewing the 2N3702 TO-92 package with the flat side facing you and leads pointing downward, the left-to-right pin order is: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base. This configuration is standardized across Fairchild's TO-92 PNP transistors and matches JEDEC TO-92 mechanical drawings. Incorrect orientation risks reverse-biasing or open-circuit operation, so visual verification before soldering is strongly advised for the 2N3702.