onsemi BC547B

Overview

BC547B from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for V_CEO = 45 V, I_C = 100 mA continuous, and h_FE = 110–290 (at I_C = 2 mA, V_CE = 5 V). It delivers low V_CE(sat) = 0.25 V (at I_C = 10 mA, I_B = 0.5 mA) and f_T = 300 MHz, making it suitable for audio preamplification, switching, and signal conditioning in consumer and industrial control circuits.

For engineers reviewing the BC547B datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain range, saturation voltage at defined drive conditions, thermal resistance (R_JA = 200 °C/W), maximum junction temperature (150 °C), and Pb-free packaging compliance per ON Semiconductor's Soldering and Mounting Techniques Reference Manual.

Technical Context

The BC547B operates as a discrete bipolar junction transistor with fixed NPN polarity and single-die construction. Its electrical behavior is defined by DC current gain (h_FE) specified across three test conditions - 2 mA, 10 mA, and 100 mA collector current - and exhibits consistent f_T = 300 MHz under standard small-signal conditions (I_C = 10 mA, V_CE = 5 V).

Thermal performance is characterized by R_JA = 200 °C/W (ambient) and R_JC = 83.3 °C/W (case), supporting operation from −55 °C to +150 °C junction temperature. The device uses epitaxial base technology and is optimized for linear amplification and medium-speed switching up to ~10 MHz in practical layouts.

Key Specifications

Pinout & Package

BC547B is housed in a through-hole TO-92 (Case 29, Style 17) package with 3 leads. Lead spacing is 2.54 mm (0.100"), body height ≤ 5.20 mm, and lead diameter 0.407–0.533 mm. The package is RoHS-compliant and available in Pb-free variants (e.g., BC547BZL1G).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC547C and 2N3904, the BC547B offers a balanced h_FE window ideal for production-stable bias networks, maintains 45 V breakdown headroom above 12 V systems, and retains full compatibility with legacy BC547 footprint designs without layout changes.

Availability

BC547B is available at Aetrix Electronics and suitable for audio preamplification, microcontroller peripheral driving, and industrial sensor signal conditioning requiring stable component supply and long-term manufacturability.

Supply support for BC547B 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC547B belongs to onsemi's legacy general-purpose transistor product line, designed for broad utility in linear amplification, switching, and interface functions across cost-sensitive and reliability-critical applications.

FAQ

What is the maximum collector-emitter voltage rating for BC547B?

The BC547B has a maximum collector-emitter voltage (V_CEO) rating of 45 V DC. This value is measured with base open and defines the absolute upper limit for voltage applied between collector and emitter before risk of avalanche breakdown. Exceeding this rating, even momentarily, may cause permanent device failure. Designers should maintain at least 20% derating margin in 12 V or 24 V systems using BC547B.

Does BC547B support Pb-free soldering processes?

Yes, BC547B is available in Pb-free variants such as BC547BZL1G, fully compliant with RoHS Directive 2011/65/EU. These versions use matte tin plating and pass JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) requirements. Reflow profiles must follow ON Semiconductor's SOLDERRM/D manual, with peak temperatures ≤ 260 °C and time above liquidus ≤ 60 seconds.

What is the typical DC current gain (h_FE) range for BC547B at 2 mA collector current?

The BC547B is binned to guarantee h_FE between 110 and 290 when tested at I_C = 2 mA and V_CE = 5 V. This range reflects manufacturing process variation and ensures predictable bias point behavior in production units. For designs sensitive to gain spread, use emitter resistors or negative feedback to stabilize operating point across the full BC547B h_FE distribution.

Can BC547B be used in switching applications above 1 MHz?

The BC547B has an f_T of 300 MHz, indicating theoretical unity-gain bandwidth, but practical switching speed is limited by stored charge and package parasitics. At I_C = 10 mA, turn-on/turn-off times are typically < 100 ns, supporting reliable operation up to ~5 MHz in well-designed circuits. For >10 MHz switching, consider RF-optimized transistors like MMBT2222A or BFR92A instead of BC547B.

How does BC547B compare to BC547A and BC547C in terms of DC current gain?

The BC547B is the mid-gain variant: BC547A specifies h_FE = 110–220, BC547B = 200–450 (per some revisions, but official datasheet states 110–290 at I_C = 2 mA), and BC547C = 420–800. All share identical V_CEO, I_C, and thermal specs. Gain binning allows designers to select precise h_FE targets without redesigning bias networks - BC547B provides optimal trade-off between gain stability and variability tolerance in production.