onsemi BC558BTFR

Overview

BC558BTFR 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 V_CEO = −30 V, I_C = −100 mA, h_FE = 200–450 (Class B), V_CE(sat) ≤ −300 mV at I_C = −10 mA/I_B = −0.5 mA, and f_T = 150 MHz - enabling use in audio preamplifiers, level shifters, and discrete logic interfaces.

For engineers reviewing the BC558BTFR datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92-3 (case 135AR) package, complementary pairing with BC548, low-noise capability among BC556–BC558 variants, and RoHS-compliant Pb-free construction suitable for legacy design refresh and industrial control signal conditioning.

Technical Context

The BC558BTFR operates as a medium-voltage, medium-current PNP bipolar junction transistor optimized for DC-coupled gain stages and saturated-switching operation. Its h_FE classification (B: 200–450) ensures predictable current amplification across production lots, while V_CEO = −30 V and V_CBO = −30 V define safe operating limits for negative-rail biasing in dual-supply systems.

Thermal performance is characterized by R_JA = 250 °C/W and P_D = 500 mW at T_A = 25 °C, with linear derating of 4.0 mW/°C above ambient. Its Cob = 6 pF and NF = 2–10 dB (at 1 kHz, I_C = −200 µA) support stable small-signal behavior in audio-frequency amplifiers and low-jitter switching nodes.

Key Specifications

Pinout & Package

BC558BTFR is housed in a TO-92-3 plastic package (case 135AR), lead-formed for through-hole mounting. Dimensions: 4.83 mm × 4.76 mm × 3.6 mm. Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter - verified per onsemi mechanical drawing 98AON13879G.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC558BTA and BC557BTF, the BC558BTFR delivers identical transistor performance in tape-and-reel format optimized for high-throughput assembly, while offering lower voltage rating than BC557BTF but tighter gain consistency than BC558BTA's bulk-handling variant.

Availability

BC558BTFR is available at Aetrix Electronics and suitable for audio preamplifiers, discrete logic level shifters, and LED sink drivers requiring stable component supply, long-term manufacturability, and RoHS-compliant sourcing.

Supply support for BC558BTFR 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BC558BTFR belongs to onsemi's legacy BC5xx family of general-purpose bipolar transistors, engineered for reliability, consistency, and ease of integration in cost-sensitive analog and mixed-signal designs.

FAQ

What is the maximum collector-emitter voltage rating for BC558BTFR?

The BC558BTFR has a guaranteed V_CEO rating of −30 V at T_A = 25 °C. This value is absolute maximum and must not be exceeded in continuous operation. Derating applies above 25 °C ambient, and transient spikes should remain within this limit to avoid junction breakdown. The BC558BTFR datasheet specifies this parameter under Absolute Maximum Ratings, confirming its suitability for −24 V systems with safety margin.

Is BC558BTFR pin-compatible with BC548?

Yes - BC558BTFR is the PNP complement to the NPN BC548, sharing identical TO-92-3 (case 135AR) package dimensions and pinout: Collector (Pin 1), Base (Pin 2), Emitter (Pin 3). This allows direct substitution in mirrored circuit topologies like push-pull output stages or differential amplifiers, provided polarity and biasing are adjusted accordingly.

Does BC558BTFR meet RoHS and lead-free requirements?

Yes, BC558BTFR is explicitly marked Pb-free, halogen-free, and BFR-free in the onsemi datasheet, and fully complies with EU RoHS Directive 2011/65/EU. Its TO-92-3 case 135AR construction uses lead-free solderable terminations and compliant molding compound, making it suitable for environmentally regulated industrial and consumer products.

What is the typical noise figure of BC558BTFR and under what conditions is it measured?

The BC558BTFR exhibits a noise figure of 2–10 dB, measured at V_CE = −5 V, I_C = −200 µA, f = 1 kHz, and R_G = 2 kΩ - per the Electrical Characteristics table in the official onsemi datasheet. This low-noise performance is validated across the BC556–BC558 series and makes BC558BTFR appropriate for sensitive front-end amplification where signal integrity is critical.

Can BC558BTFR be used in switching applications, and what is its saturation voltage?

Yes, BC558BTFR is rated for switching use with V_CE(sat) ≤ −300 mV at I_C = −10 mA and I_B = −0.5 mA, and ≤ −650 mV at I_C = −100 mA and I_B = −5 mA. These values confirm robust saturation behavior, enabling efficient on-state conduction in relay drivers, LED sinks, and digital logic interfaces without excessive power dissipation.