onsemi BC368_L34Z

Overview

BC368_L34Z from Fairchild Semiconductor is an NPN general-purpose bipolar junction transistor designed for medium-power amplification and switching applications, with a continuous collector current rating of 2.0 A, V_CEO = 20 V, and DC current gain (h_FE) ranging from 50 to 375 at I_C = 5 mA–1.0 A. It is commonly used in relay drivers, power supply control stages, and low-frequency audio amplifiers.

For engineers reviewing the BC368_L34Z datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-92 package thermal resistance (R_θJA = 200 °C/W), saturation voltage (V_CE(sat) = 0.5 V at I_C = 1.0 A), and f_T = 45 MHz bandwidth capability.

Technical Context

The BC368_L34Z operates as a silicon NPN BJT fabricated using Fairchild's Process 37, optimized for stable DC gain and low saturation voltage across -55°C to +150°C junction temperature range. Its breakdown ratings-V_(BR)CEO = 20 V, V_(BR)CES = 25 V, and V_(BR)EBO = 5.0 V-define safe operating limits under open-base and open-emitter conditions.

Thermal design relies on its R_θJC = 83.3 °C/W and R_θJA = 200 °C/W values, with power dissipation derated linearly above 25°C at 5.0 mW/°C. The device exhibits typical pulsed h_FE > 300 at I_C = 0.1 A and maintains usable gain up to 45 MHz at I_C = 10 mA.

Key Specifications

Pinout & Package

BC368_L34Z is housed in a through-hole TO-92 package with standard three-terminal configuration: Emitter, Base, and Collector arranged in linear pin order (viewed from flat side, leads down). Package dimensions conform to JEDEC TO-92 outline, enabling compatibility with legacy PCB footprints and manual soldering processes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose amplifier applications.

Compared with BC368_L34Z, BC337-40 offers higher voltage tolerance without sacrificing thermal or mechanical compatibility, while 2N2222A trades current capacity for significantly higher f_T, making it unsuitable for 1–2 A switching but advantageous in RF-sensitive designs.

Availability

BC368_L34Z is available at Aetrix Electronics and suitable for relay driver circuits, DC-DC converter switches, and audio pre-amplifier stages requiring stable component supply and long-term obsolescence management.

Supply support for BC368_L34Z 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 BC368_L34Z belongs to Fairchild's general-purpose BJT family, engineered for cost-effective, thermally robust amplification and switching in industrial and consumer electronics.

FAQ

What is the maximum continuous collector current for BC368_L34Z?

The BC368_L34Z supports a maximum continuous collector current of 2.0 A at T_A = 25°C with proper heatsinking. At elevated ambient temperatures, current must be reduced per the 5.0 mW/°C derating curve to maintain junction temperature below 150°C. This rating is validated under steady-state DC conditions-not pulsed operation-so designers should consult Fairchild's application notes for transient duty-cycle guidance specific to BC368_L34Z.

Is BC368_L34Z suitable for switching inductive loads like relays?

Yes, BC368_L34Z is widely used for relay driving due to its 2.0 A I_C rating and low V_CE(sat) of 0.5 V at 1.0 A. However, an external flyback diode must be placed across the relay coil to suppress inductive kickback, as BC368_L34Z has no integrated protection. Its V_(BR)CEO = 20 V sets the absolute clamp voltage limit, so coil supply must remain within this margin unless clamped externally. This makes BC368_L34Z appropriate for 12 V relay systems with proper snubbing.

What is the package type and pin configuration of BC368_L34Z?

BC368_L34Z uses the standard through-hole TO-92 package with three leads in linear order: Emitter (pin 1), Base (pin 2), Collector (pin 3), viewed from the flat side with leads pointing downward. This matches JEDEC TO-92 outline dimensions and is mechanically and electrically compatible with other TO-92 NPN transistors such as BC337 and 2N2222A, though electrical parameters differ. No alternate packages (e.g., SOT-23) exist for BC368_L34Z.

Does BC368_L34Z have a specified gain-bandwidth product (f_T)?

Yes, BC368_L34Z has a specified f_T of 45 MHz at I_C = 10 mA, V_CE = 5.0 V, and f = 35 MHz test condition. This value reflects its small-signal AC performance and indicates usable amplification bandwidth up to several megahertz in properly biased common-emitter configurations. Gain rolls off at 20 dB/decade beyond f_T, so BC368_L34Z is not recommended for RF or high-speed digital applications exceeding 10 MHz, but remains effective for audio and low-frequency control signals.

What is the operating temperature range for BC368_L34Z?

The BC368_L34Z is rated for junction and storage temperature from -55°C to +150°C. This wide range supports deployment in harsh environments such as automotive engine compartments, industrial motor controls, and outdoor power equipment. Ambient temperature operation depends on power dissipation and PCB thermal design; at 625 mW, the junction will rise 125°C above ambient (200 °C/W × 0.625 W), limiting safe T_A to 25°C unless heatsinking improves R_θJA. Derating curves in the BC368_L34Z datasheet must be followed for reliable long-term operation.