onsemi BC307

Overview

BC307 from Fairchild Semiconductor is a PNP epitaxial silicon transistor designed for linear amplification and switching in low-voltage analog circuits, with confirmed V_CEO = −45 V, I_C = −100 mA, P_C = 500 mW, h_FE range 120–800 (Class A–C), and f_T = 130 MHz - used in audio preamplifier stages and relay driver interfaces.

For engineers reviewing the BC307 datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-92 package, PNP polarity, −45 V V_CEO, −100 mA I_C, and noise figure of 2 dB at 1 kHz - critical for low-noise small-signal amplification and discrete logic-level inversion.

Technical Context

The BC307 operates as a general-purpose PNP bipolar junction transistor with fixed-emitter biasing capability and DC current gain controlled by h_FE classification (A/B/C). Its V_BE(sat) = −0.55 to −0.7 V and V_CE(sat) = −0.5 V at I_C = −10 mA / I_B = −0.5 mA define switching thresholds in saturated-mode applications.

It exhibits Cob = 6 pF and Cib = 12 pF at 1 MHz, supporting stable operation up to 130 MHz f_T, and maintains thermal stability with T_J = 150°C maximum junction temperature and T_STG = −55 to +150°C storage range.

Key Specifications

Pinout & Package

BC307 is housed in a standard through-hole TO-92 package (3.60 × 4.58 × 14.47 mm), with lead spacing matching JEDEC TO-92 mechanical outline and compatible with manual soldering and wave soldering processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC557 and 2N3906, the BC307 offers the best balance of voltage rating, gain flexibility (three h_FE classes), and low-noise performance - making it preferred for audio-sensitive and gain-matched analog designs.

Availability

BC307 is available at Aetrix Electronics and suitable for audio preamplifier stages, relay driver interfaces, discrete logic inverters, and current mirror references requiring stable component supply and long-term obsolescence management.

Supply support for BC307 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 semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The BC307 belongs to Fairchild's legacy general-purpose bipolar transistor family, engineered for cost-effective, reliable amplification and switching in consumer, industrial, and automotive auxiliary circuits.

FAQ

What is the maximum collector-emitter voltage rating for BC307?

The BC307 has a maximum collector-emitter voltage (V_CEO) rating of −45 V at T_A = 25°C. This value is specified with base open and defines the upper limit for safe operation in common-emitter configurations. Exceeding this voltage risks avalanche breakdown. The BC307 datasheet confirms this parameter under "Absolute Maximum Ratings" and "Electrical Characteristics" sections.

Is BC307 suitable for low-noise audio amplification?

Yes, the BC307 is suitable for low-noise audio amplification, with a noise figure of 2 dB measured at V_CE = −5 V, I_C = −0.2 mA, R_G = 2 kΩ, and f = 1 kHz. This specification is explicitly stated in the "Electrical Characteristics" table for BC307/BC308. Its low V_BE(on) and stable h_FE further support consistent gain in preamplifier topologies.

What package type does BC307 use and what are its key mechanical dimensions?

The BC307 uses a TO-92 plastic package with standardized lead spacing. Key dimensions include overall length 14.47 ±0.40 mm, body width 3.60 ±0.20 mm, and lead pitch 1.27 mm (typical). These values are documented in the "Package Dimensions" section of the Fairchild BC307/308/309 datasheet Rev. A2.

How does h_FE classification affect BC307 selection in circuit design?

The BC307 is offered in three h_FE classifications (A/B/C) with ranges 120–220, 180–460, and 380–800 respectively. Selecting a specific class determines base drive requirements and gain predictability: Class A suits low-gain, high-stability biasing; Class C enables high-gain amplification with tighter tolerance. This binning is confirmed in the "Electrical Characteristics" table.

Can BC307 be used as a direct replacement for BC308 or BC309 in existing designs?

No - BC307 is not a direct replacement for BC308 or BC309 due to differing absolute maximum ratings: BC307 has V_CEO = −45 V and V_CES = −50 V, while BC308/309 are rated at −25 V and −30 V respectively. Additionally, BC309 specifies lower noise (4 dB at 30–15 kHz) and different NF test conditions. Substitution requires validation against voltage, gain, and noise requirements.