onsemi BC556BTFR

Overview

BC556BTFR from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and linear amplification in low-to-medium power circuits. It features V_CEO = −65 V, I_C = −100 mA, h_FE = 110–800 (Class B), f_T = 150 MHz, and operates with V_BE(on) ≈ −660 mV at I_C = −2 mA - commonly used in discrete amplifier stages, level-shifting interfaces, and relay drivers.

For engineers reviewing the BC556BTFR datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92-3 (case 135AR) package, −65 V collector-emitter breakdown rating, Class B h_FE range, low-noise capability relative to BC556/557/558 variants, and compatibility with complementary NPN BC546–BC550 series.

Technical Context

The BC556BTFR implements a standard PNP bipolar junction structure optimized for DC amplification and saturated switching. Its h_FE classification (B: 200–450) ensures predictable current gain in bias-stable amplifier configurations, while V_CE(sat) ≤ −300 mV at I_C = −10 mA / I_B = −0.5 mA supports efficient low-loss switching.

Thermal performance is defined by R_JA = 250 °C/W (FR-4 PCB, 76 mm × 114 mm), PD = 500 mW at 25°C with 4.0 mW/°C derating - confirming suitability for ambient-temperature-stable through-hole analog and logic interface designs without forced cooling.

Key Specifications

Pinout & Package

BC556BTFR is housed in a TO-92-3 plastic package (case 135AR), lead-formed for through-hole mounting. Dimensions: 4.83 mm × 4.76 mm footprint with standardized lead spacing.

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, BC556BTFR delivers the highest V_CEO rating in its family while maintaining identical gain binning and package - making it the preferred choice for robustness-critical 48 V telecom, industrial control, and legacy analog designs where voltage headroom is non-negotiable.

Availability

BC556BTFR is available at Aetrix Electronics and suitable for industrial control systems, audio signal conditioning circuits, and relay interface modules requiring stable component supply and long-term manufacturability.

Supply support for BC556BTFR 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 BC556BTFR belongs to onsemi's legacy general-purpose bipolar transistor family, engineered for reliability and consistency in cost-sensitive, high-volume analog and interface applications across decades of industrial deployment.

FAQ

What is the maximum collector-emitter voltage rating for BC556BTFR?

The BC556BTFR has a guaranteed V_CEO rating of −65 V at T_A = 25°C. This specifies the maximum reverse-biased voltage the transistor can withstand between collector and emitter with the base open before entering avalanche breakdown. Exceeding this value risks permanent device failure, especially under transient conditions or elevated temperatures.

Is BC556BTFR pin-compatible with BC546–BC550 NPN transistors?

BC556BTFR is not pin-compatible with BC546–BC550 NPN transistors due to opposite polarity - though both share the TO-92-3 (135AR) physical package and identical pin numbering (1=Collector, 2=Base, 3=Emitter), their circuit roles are complementary. BC556BTFR must be used in PNP-configured circuits, while BC546–BC550 serve NPN roles; direct substitution without topology revision will cause functional failure.

What does the "B" in BC556BTFR indicate?

The "B" in BC556BTFR denotes the h_FE gain classification bin: 200–450 at I_C = −2 mA and V_CE = −5 V. This binning ensures tighter gain distribution than Class A (110–220) or Class C (420–800), improving predictability in bias-sensitive amplifier and switching designs without requiring gain measurement or trimming during manufacturing.

Does BC556BTFR support high-frequency signal amplification?

Yes, BC556BTFR supports high-frequency signal amplification up to its f_T of 150 MHz, making it suitable for audio-frequency amplifiers (20 Hz–20 kHz), IF stages in AM receivers, and low-speed digital signal buffering. However, its 6 pF Cob and gain roll-off beyond 10 MHz mean it is not intended for RF power amplification or GHz-range applications.

What is the thermal resistance of BC556BTFR in standard PCB layout?

BC556BTFR has a junction-to-ambient thermal resistance (R_JA) of 250 °C/W when mounted on a standard FR-4 PCB measuring 76 mm × 114 mm × 1.57 mm with minimum land pattern. This means a 500 mW power dissipation raises the junction temperature by 125 °C above ambient - so operation at full power is only safe below 25°C ambient unless heatsinking or airflow is added.