onsemi BC556BBU

Overview

BC556BBU from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and linear amplification in low-to-medium power circuits. It features −65 V collector-emitter breakdown voltage (V_CEO), 110–800 DC current gain (h_FE), and −100 mA continuous collector current, operating reliably up to 150°C junction temperature. It is commonly used in discrete amplifier stages, relay drivers, and level-shifting interfaces in industrial control modules.

For engineers reviewing the BC556BBU datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO = −65 V, h_FE Class B (200–450), TO-92−3 package with standardized leadform, and RoHS-compliant Pb-free construction per onsemi's Rev. 3 datasheet (June 2024).

Technical Context

This device operates as a medium-voltage, medium-current PNP bipolar junction transistor with fixed emitter-base and collector-base junction structures. Its h_FE classification (B) ensures predictable current amplification across IC = −2 mA to −100 mA, while V_CE(sat) ≤ −300 mV at IC = −10 mA / IB = −0.5 mA enables efficient saturation in switching applications.

Thermal performance is defined by R_JA = 250°C/W on standard FR-4 PCB (76 mm × 114 mm), and its 500 mW total dissipation derates linearly at 4.0 mW/°C above 25°C ambient. The −5 V V_EBO rating limits base-emitter reverse bias, constraining use in high-impedance bias networks without clamping.

Key Specifications

Pinout & Package

BC556BBU is housed in a TO-92−3 plastic package (Case 135AN), with straight leads and Pb-free finish. Dimensions are 4.825 mm × 4.76 mm footprint, compatible with standard through-hole assembly processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC557BTA and BC807-25, BC556BBU offers the highest V_CEO among TO-92 PNP transistors in its family, making it uniquely suited for −48 V telecom and high-reliability industrial power rails where voltage headroom is critical - without requiring SMT requalification.

Availability

BC556BBU is available at Aetrix Electronics and suitable for industrial control systems, audio signal conditioning circuits, and relay driver modules requiring stable component supply and long-term obsolescence management.

Supply support for BC556BBU 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 manufacturer specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC556 series belongs to onsemi's legacy general-purpose bipolar transistor product line, engineered for cost-sensitive, high-reliability discrete amplification and switching in industrial and telecom infrastructure where proven performance and long-lifecycle support are essential.

FAQ

What is the maximum collector-emitter voltage rating for BC556BBU?

The BC556BBU has a guaranteed V_CEO rating of −65 V at T_A = 25°C, as specified in onsemi's June 2024 Rev. 3 datasheet. This rating applies under DC conditions with no secondary breakdown limitations; designers must observe SOA curves for pulsed operation. Exceeding −65 V risks irreversible junction breakdown. The BC556BBU is therefore preferred over lower-voltage variants like BC557BTA (−45 V) in −48 V systems.

Is BC556BBU RoHS compliant and lead-free?

Yes, BC556BBU is explicitly marked Pb-free and RoHS compliant per onsemi's datasheet, meeting EU Directive 2011/65/EU requirements. It also satisfies halogen-free and BFR-free specifications. The TO-92−3 Case 135AN package uses matte tin plating on leads, and all internal materials are qualified for lead-free soldering processes up to 260°C peak temperature.

What is the h_FE range for BC556BBU, and how is it binned?

The BC556BBU is h_FE Class B, with a guaranteed DC current gain range of 200 to 450 at V_CE = −5 V and I_C = −2 mA. This binning is confirmed per onsemi's h_FE Classification table in the datasheet. Units are tested and sorted at wafer level; no unit outside this range is shipped as BC556BBU. This tight bin ensures predictable biasing in production amplifier circuits.

Can BC556BBU replace BC556ABU in existing designs?

Yes, BC556BBU is a direct functional and mechanical replacement for BC556ABU, sharing identical TO-92−3 Case 135AN packaging, pinout, and absolute maximum ratings. The only difference is h_FE binning: BC556ABU is Class A (110–220), while BC556BBU is Class B (200–450). Designers should verify that the higher minimum h_FE does not cause unintended bias shift in sensitive analog stages.

What thermal derating applies to BC556BBU above 25°C ambient?

BC556BBU's total device dissipation (P_D) derates linearly at 4.0 mW/°C above 25°C ambient, based on R_JA = 250°C/W on a standard FR-4 PCB (76 mm × 114 mm). At 75°C ambient, maximum allowable P_D drops to 300 mW. Junction temperature must remain ≤ 150°C; designers should calculate actual T_J using measured power and board-specific thermal resistance.