onsemi BC558BTF

Overview

BC558BTF from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and amplification in low-to-medium 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 BC558BTF datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-92-3 (Case 135AR) package, complementary pairing with BC548, verified noise figure of 2–10 dB at 1 kHz, and RoHS-compliant Pb-free construction suitable for legacy design refresh and industrial control signal conditioning.

Technical Context

The BC558BTF operates as a medium-gain, medium-voltage PNP bipolar junction transistor optimized for linear amplification and saturated switching. Its h_FE classification B (200–450) ensures predictable DC bias stability across temperature, while V_CEO = −30 V and V_CBO = −30 V define safe operation in negative-rail circuits up to −24 V supply rails.

Thermal performance is characterized 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 - supporting continuous operation in ambient temperatures up to +85°C when mounted per standard TO-92 land patterns. Cob = 6 pF at V_CB = −10 V enables stable high-frequency gain without unintended oscillation in audio-band designs.

Key Specifications

Pinout & Package

BC558BTF 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 transistor applications.

Compared with BC558CTA and BC557BTF, BC558BTF offers balanced gain and voltage rating for cost-sensitive, mid-range industrial controls - avoiding overdesign in 24 V systems while maintaining compatibility with BC548-based complementary stages.

Availability

BC558BTF is available at Aetrix Electronics and suitable for audio signal conditioning, discrete logic implementation, and LED driver circuits requiring stable component supply across extended production lifecycles.

Supply support for BC558BTF 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, and cloud infrastructure markets.

The BC558BTF belongs to onsemi's legacy general-purpose bipolar transistor family, engineered for reliability and manufacturability in cost-sensitive, high-volume applications such as consumer electronics, industrial controls, and repair/maintenance kits.

FAQ

What is the maximum collector-emitter voltage rating for BC558BTF?

The BC558BTF has a maximum collector-emitter voltage (V_CEO) rating of −30 V, verified per onsemi's Absolute Maximum Ratings table. This rating applies at T_A = 25°C and defines the upper limit for safe DC operation in negative-rail configurations. Exceeding −30 V risks avalanche breakdown and permanent device degradation. Derating is not specified beyond standard thermal limits, so design margins should maintain ≤ −24 V in production systems using BC558BTF.

Is BC558BTF pin-compatible with BC548?

Yes, BC558BTF is complementary - not pin-compatible - with BC548. Both use TO-92-3 (Case 135AR) packaging with identical pinout (Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter), but BC548 is NPN while BC558BTF is PNP. Their matched characteristics (gain range, V_CE(sat), f_T) allow direct pairing in push-pull or differential circuits, though polarity reversal must be accounted for in schematic layout and biasing when using BC558BTF.

What is the typical DC current gain (h_FE) of BC558BTF at 2 mA collector current?

The BC558BTF exhibits a typical DC current gain (h_FE) of 330 at V_CE = −5 V and I_C = −2 mA, per onsemi's Electrical Characteristics table. Its Class B binning specifies a minimum of 200 and maximum of 450 under those conditions. This gain value is stable across −55°C to +150°C junction temperatures, making BC558BTF suitable for bias-critical amplifier stages where predictable current amplification is required without active feedback compensation.

Does BC558BTF meet RoHS and lead-free requirements?

Yes, BC558BTF is explicitly marked as Pb-free, halogen-free, and BFR-free in onsemi's datasheet, and complies with EU RoHS Directive 2011/65/EU. The device uses lead-free matte tin plating on leads and RoHS-compliant molding compound. No exemptions apply, and the part is suitable for use in consumer, industrial, and medical devices requiring full environmental compliance - confirmed by onsemi's material declarations and packaging documentation for Case 135AR.

What is the thermal resistance (R_JA) of BC558BTF on a standard FR-4 PCB?

The thermal resistance from junction to ambient (R_JA) for BC558BTF is 250 °C/W when mounted on a standard FR-4 PCB measuring 76 mm × 114 mm × 1.57 mm with minimum land pattern, as defined in onsemi's Thermal Characteristics table. This value assumes natural convection cooling and no heatsinking. At full 500 mW dissipation, this results in a 125°C junction-to-ambient rise above ambient - requiring ambient temperature limitation to ≤ +60°C for safe continuous operation with BC558BTF.