onsemi BC547B_L34Z

Overview

BC547B_L34Z from ON Semiconductor is an NPN epitaxial silicon transistor designed for general-purpose switching and low-noise amplification in discrete analog circuits. It delivers V_CEO = 45 V, h_FE = 200–450 (Class B), f_T = 300 MHz, and operates up to 150°C junction temperature in TO-92 packaging - commonly used in signal conditioning stages of sensor interfaces and power supply control loops.

For engineers reviewing the BC547B_L34Z datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain consistency at 2 mA/5 V bias, low V_CE(sat) under 10 mA drive, noise figure below 10 dB at 1 kHz, and compatibility with through-hole PCB assembly workflows requiring JEDEC TO-92 footprint compliance.

Technical Context

This device belongs to the legacy BC546–BC550 family originally developed by Fairchild and now maintained by ON Semiconductor. Its epitaxial base construction enables stable h_FE across temperature and supports both linear amplification (e.g., preamplifier stages) and saturated switching (e.g., relay drivers) with validated performance at I_C ≤ 100 mA and P_C ≤ 500 mW.

The BC547B_L34Z shares identical absolute maximum ratings and electrical characteristics with BC547B variants listed in Rev. 1.1.1 datasheet - including V_CBO = 50 V, V_EBO = 6 V, and C_ob = 3.5–6.0 pF - confirming functional equivalence despite underscore-to-dash nomenclature update per ON Semiconductor's Fairchild integration policy.

Key Specifications

Pinout & Package

BC547B_L34Z uses the industry-standard JEDEC TO-92 3-lead through-hole package with straight lead configuration (bulk type). Pin identification follows conventional emitter-down orientation when flat side faces viewer and leads point downward: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC547C_L34Z and PN2222A, BC547B_L34Z offers optimal balance of gain predictability (200–450), noise performance (≤10 dB), and thermal margin (150°C), making it preferred for industrial signal chain designs where repeatability matters.

Availability

BC547B_L34Z is available at Aetrix Electronics and suitable for industrial automation, sensor interface design, and legacy equipment repair requiring stable component supply and long-term obsolescence management.

Supply support for BC547B_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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power and sensing solutions for automotive, industrial, cloud computing, and consumer electronics markets.

The BC547B_L34Z belongs to ON Semiconductor's legacy bipolar transistor product line, engineered for reliability in general-purpose analog signal processing and discrete switching applications across harsh environments.

FAQ

What is the maximum collector-emitter voltage rating for BC547B_L34Z?

The BC547B_L34Z has a maximum collector-emitter voltage (V_CEO) rating of 45 V. This value is specified under DC conditions at T_A = 25°C and defines the upper limit of voltage that can be safely applied between collector and emitter while keeping the base open. Exceeding this rating risks permanent breakdown and must be avoided in all operating conditions, including transient spikes.

Does BC547B_L34Z have a defined h_FE classification, and what does it mean for circuit design?

Yes, BC547B_L34Z is classified as Class B with a guaranteed h_FE range of 200 to 450 at V_CE = 5 V and I_C = 2 mA. This binning enables predictable DC biasing in amplifier and switch circuits - designers can size base resistors knowing minimum gain will be 200, reducing need for post-production trimming or feedback compensation in BC547B_L34Z-based designs.

Can BC547B_L34Z be used in low-noise audio applications?

Yes, BC547B_L34Z is suitable for low-noise audio applications such as microphone preamplifiers, with a noise figure (NF) of 2.0–10.0 dB measured at V_CE = 5 V, I_C = 200 μA, f = 1 kHz, and R_G = 2 kΩ. Its epitaxial structure and controlled manufacturing process ensure consistent noise performance across units, making BC547B_L34Z appropriate for cost-sensitive analog front-ends where SNR > 60 dB is required.

What package type does BC547B_L34Z use, and how is it oriented on PCB?

BC547B_L34Z uses the JEDEC TO-92 3-lead through-hole package. When mounted with the flat side facing the viewer and leads pointing downward, the pinout is: Pin 1 (left) = Collector, Pin 2 (center) = Base, Pin 3 (right) = Emitter. This orientation matches standard silkscreen markings on PCBs designed for BC547-series transistors, ensuring correct placement during manual or automated assembly of BC547B_L34Z.

How does BC547B_L34Z differ from BC547A and BC547C variants?

BC547B_L34Z differs from BC547A and BC547C solely in its h_FE classification: BC547A = 110–220, BC547B_L34Z = 200–450, BC547C = 420–800. All share identical absolute maximum ratings, thermal characteristics, pinout, and package. The BC547B_L34Z variant provides mid-range gain stability ideal for applications needing reliable amplification without excessive gain variability - a key differentiator when selecting among BC547 variants.