onsemi BC556TFR

Overview

BC556TFR from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and linear amplification in low-power analog and digital circuits. It features −65 V collector-emitter voltage (V_CEO), −80 V collector-base voltage (V_CBO), 500 mW power dissipation, DC current gain (h_FE) ranging from 110 to 800 at −2 mA collector current, and operates up to 150 MHz current gain bandwidth (f_T). It is commonly used in discrete amplifier stages, level shifters, and load switches in industrial control modules.

For engineers reviewing the BC556TFR datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-92-3 package compatibility, PNP polarity, −65 V breakdown rating, h_FE classification (B-grade), and RoHS-compliant Pb-free construction.

Technical Context

The BC556TFR is a discrete bipolar junction transistor with fixed PNP polarity and single-element structure. Its operation relies on minority-carrier injection from emitter to base and collection at the collector under reverse-biased V_CE. The device exhibits low noise performance (2–10 dB NF at 1 kHz) and supports both DC biasing and small-signal AC amplification.

Thermal design is constrained by R_JA = 250 °C/W and a maximum junction temperature of 150 °C. Derating begins above 25 °C at 4.0 mW/°C, requiring careful thermal management in continuous-conduction applications such as relay drivers or constant-current sources.

Key Specifications

Pinout & Package

BC556TFR is housed in a TO-92-3 plastic package (Case 135AR), lead-formed configuration, with standard through-hole mounting. Pin identification follows the marking diagram: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC556BTA and BC557BTF, BC556TFR offers identical performance to BC556BTA but with automated tape-and-reel delivery, while providing 20 V higher V_CEO headroom than BC557BTF-critical for robustness in legacy infrastructure and safety-critical switching.

Availability

BC556TFR is available at Aetrix Electronics and suitable for industrial control modules, audio preamplifiers, and relay driver circuits requiring stable component supply, long-term lifecycle continuity, and RoHS-compliant sourcing.

Supply support for BC556TFR 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, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The BC556TFR belongs to onsemi's legacy BC5xx family of general-purpose bipolar transistors, engineered for reliability and consistency in discrete analog signal conditioning and low-power switching across decades of industrial deployment.

FAQ

What is the package type and lead configuration of BC556TFR?

BC556TFR uses the TO-92-3 package (Case 135AR) with lead-formed (bent) leads optimized for automated tape-and-reel placement. Its mechanical dimensions are 4.83 mm × 4.76 mm, and pinout is standardized: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter. This configuration ensures compatibility with standard through-hole PCB footprints and pick-and-place equipment.

Is BC556TFR suitable for high-frequency amplifier designs?

BC556TFR has a current gain bandwidth product (f_T) of 150 MHz at −5 V V_CE and −10 mA I_C, making it usable in low-to-moderate RF applications such as IF amplifiers or oscillator buffers. However, its 6 pF output capacitance and lack of specified S-parameters limit use beyond ~50 MHz in impedance-controlled layouts. For BC556TFR, small-signal gain rolls off significantly above 30 MHz in typical common-emitter configurations.

What is the h_FE classification for BC556TFR, and how does it affect circuit design?

BC556TFR is classified as "B" grade, meaning its DC current gain (h_FE) falls within 200–450 at −2 mA I_C and −5 V V_CE. This mid-range gain band allows predictable base resistor sizing in switching circuits while avoiding excessive sensitivity to temperature drift. Designers using BC556TFR should verify saturation with I_B ≥ I_C/20 to ensure robust turn-on across process variation.

Can BC556TFR replace BC557 in an existing design?

BC556TFR cannot be a direct drop-in replacement for BC557 due to differing absolute maximum ratings: BC556TFR supports −65 V V_CEO, whereas BC557 is rated for only −45 V. Substituting BC556TFR into a BC557-design may be safe electrically, but layout and thermal validation are required since both share the same TO-92-3 package and pinout. Always confirm voltage stress margins before substitution.

Does BC556TFR meet modern environmental compliance standards?

Yes, BC556TFR is explicitly marked Pb-free, halogen-free, and BFR-free in the official onsemi datasheet, and fully complies with RoHS Directive 2011/65/EU. Its TO-92-3 package uses matte tin lead plating and green molding compound, supporting lead-free soldering processes up to 260 °C peak temperature without degradation of parametric performance or reliability.