onsemi BC556BZL1G

Overview

BC556BZL1G from onsemi is a PNP silicon small-signal amplifier transistor in TO-92 package, rated for −65 V collector-emitter voltage, −100 mA continuous collector current, and 625 mW power dissipation at 25°C ambient. It delivers DC current gain (h_FE) of 120–420 at −10 mA/−5 V, with f_T = 280 MHz and V_CE(sat) ≤ −0.3 V at −10 mA/−0.5 mA drive - used in discrete audio preamplifier stages, level-shifting circuits, and low-power switching in industrial control interfaces.

For engineers reviewing the BC556BZL1G datasheet, pinout, applications, or equivalent options, key selection criteria include its −65 V V_CEO, guaranteed h_FE bin (B-series), Pb-free TO-92 packaging, thermal resistance (R_JA = 200°C/W), and compatibility with legacy BC556 design footprints requiring PNP amplification with moderate bandwidth and low saturation voltage.

Technical Context

The BC556BZL1G operates as a general-purpose PNP bipolar junction transistor optimized for linear amplification and switching in low-to-medium frequency analog and digital circuits. Its electrical behavior is defined by fixed-base-current-driven operation, with specified h_FE min/max across three test conditions (−10 A, −2 mA, −100 mA) and validated V_BE(on) range of −0.55 V to −0.7 V at −2 mA.

Thermal performance is characterized by R_JA = 200°C/W and R_JC = 83.3°C/W, supporting operation from −55°C to +150°C junction temperature. Safe operating area (SOA) curves confirm reliability up to −65 V/−100 mA single-pulse conditions, with second-breakdown and thermal limits explicitly plotted in the datasheet.

Key Specifications

Pinout & Package

BC556BZL1G uses the TO-92 (Case 29-11, Style 17) package with bent leads and Pb-free finish. Dimensions conform to ANSI Y14.5M-1982, with body height 4.45–5.20 mm, lead pitch 2.54 mm, and seating plane reference per standard mechanical outline.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP small-signal amplifier applications.

Compared with BC556BZL1G, BC557BZL1G offers reduced voltage headroom but improved h_FE uniformity for precision biasing, while MMBT5551LT1G provides double the V_CEO at the cost of TO-92 compatibility and higher gain variation - making BC556BZL1G optimal for legacy-compatible −65 V amplifier designs needing proven thermal and SOA behavior.

Availability

BC556BZL1G is available at Aetrix Electronics and suitable for industrial control interfaces, discrete audio signal chains, and low-power switching applications requiring stable component supply, long-term obsolescence management, and RoHS-compliant manufacturing.

Supply support for BC556BZL1G 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 management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC556BZL1G belongs to onsemi's legacy BC5xx PNP/NPN amplifier transistor family, designed for cost-sensitive, high-reliability discrete analog functions in industrial automation, instrumentation, and legacy system replacements.

FAQ

What is the maximum collector-emitter voltage rating for BC556BZL1G?

The BC556BZL1G has a maximum collector-emitter voltage (V_CEO) rating of −65 V DC. This value is confirmed in the Absolute Maximum Ratings table and verified under test condition IC = −2.0 mA, IB = 0. Exceeding this voltage risks avalanche breakdown and permanent device damage. Designers must ensure all operating conditions-including transients-remain within this limit, especially in inductive load switching or high-voltage bias networks where BC556BZL1G is deployed.

Does BC556BZL1G have a guaranteed DC current gain range, and what test conditions apply?

Yes, BC556BZL1G is binned as a "B-series" device with a guaranteed h_FE range of 120–420 when tested at IC = −10 mA and VCE = −5.0 V. Additional h_FE min/max values are specified at −2 mA and −100 mA, but the −10 mA/−5 V condition is the primary gain specification used for circuit design. This binning ensures predictable base resistor calculation and gain stability across production lots of BC556BZL1G.

What is the thermal resistance from junction to ambient (R_JA) for BC556BZL1G, and how does it affect power dissipation?

The thermal resistance from junction to ambient (R_JA) for BC556BZL1G is 200°C/W, measured in free-air conditions per the datasheet's Thermal Characteristics table. At 25°C ambient, this limits continuous power dissipation to 625 mW. For every 1°C rise in ambient temperature above 25°C, allowable power drops by 5.0 mW. This directly constrains BC556BZL1G's use in sealed enclosures or high-temperature environments unless derated accordingly.

Is BC556BZL1G compatible with standard TO-92 footprints, and what is its pin configuration?

Yes, BC556BZL1G uses the standard TO-92 package (Case 29-11, Style 17) with pin 1 = Collector, pin 2 = Base, pin 3 = Emitter - matching industry-standard layouts for BC556-family devices. Mechanical drawings confirm lead pitch (2.54 mm), body dimensions (4.45–5.20 mm height), and seating plane alignment comply with ANSI Y14.5M-1982. No PCB modification is required when replacing legacy BC556 variants with BC556BZL1G.

What is the typical transition frequency (f_T) of BC556BZL1G, and how is it measured?

The typical transition frequency (f_T) of BC556BZL1G is 280 MHz, measured under conditions IC = −10 mA, VCE = −5.0 V, and f = 100 MHz per the Electrical Characteristics table. This parameter reflects the frequency at which the small-signal current gain (h_fe) drops to unity, confirming suitability for audio amplification and medium-speed switching. The f_T value is validated across production lots and remains stable within ±15% over the −55°C to +150°C junction temperature range for BC556BZL1G.