onsemi BC558B_J35Z

Overview

BC558B_J35Z 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 BC558B_J35Z datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92−3 (Case 135AR) package, complementary pairing with BC548/BC549 NPN transistors, low-noise capability (NF = 2–10 dB), and −30 V collector-emitter breakdown rating for mid-voltage bias networks.

Technical Context

The BC558B_J35Z operates as a medium-gain, medium-speed PNP bipolar junction transistor optimized for DC-coupled amplification and saturated switching. Its h_FE classification (B: 200–450) ensures predictable current gain across production lots, while V_BE(on) = −600 to −750 mV at I_C = −2 mA supports stable biasing in emitter-follower and common-emitter configurations.

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, non-heatsinked applications such as sensor signal conditioning and LED driver stages.

Key Specifications

Pinout & Package

BC558B_J35Z is housed in a TO-92−3 plastic package (Case 135AR), lead-formed, with standardized pin assignment: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC558C and BC557B, BC558B_J35Z offers the most balanced trade-off of gain consistency, voltage rating, and noise performance for general-purpose 5–24 V analog and logic interface designs - avoiding over-specification while maintaining design margin.

Availability

BC558B_J35Z is available at Aetrix Electronics and suitable for audio preamplifiers, discrete logic inverters, and sensor bias networks requiring stable component supply, long-term manufacturability, and RoHS-compliant sourcing.

Supply support for BC558B_J35Z 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, high-performance silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The BC556–BC560 family was engineered for cost-sensitive, high-reliability discrete analog functions - emphasizing gain consistency, thermal stability, and compatibility with legacy through-hole assembly processes.

FAQ

What is the maximum collector-emitter voltage rating for BC558B_J35Z?

The BC558B_J35Z has a maximum collector-emitter voltage (V_CEO) rating of −30 V. This value is specified under standard test conditions (T_A = 25°C) and defines the upper limit of reverse bias the transistor can withstand in common-emitter configuration without breakdown. Exceeding this rating risks permanent damage or parametric shift. The BC558B_J35Z must not be used in circuits where V_CE may exceed −30 V under any operating condition, including transients.

Is BC558B_J35Z pin-compatible with BC548 or BC549 NPN transistors?

Yes - BC558B_J35Z shares the same TO-92−3 (Case 135AR) package and pinout (C-B-E) as BC548 and BC549, making it a complementary PNP counterpart. This enables direct use in push-pull output stages, differential amplifiers, and level-shifting pairs without PCB layout changes. However, polarity reversal must be observed in schematic placement and bias network design to maintain functional equivalence.

What is the typical noise figure of BC558B_J35Z and at what conditions is it measured?

The BC558B_J35Z exhibits a noise figure (NF) of 2–10 dB, measured at V_CE = −5 V, I_C = −200 µA, f = 1 kHz, and R_G = 2 kΩ. This specification applies specifically to the BC556/BC557/BC558 variants per the onsemi datasheet. The low-noise performance makes BC558B_J35Z suitable for sensitive analog front-end applications such as microphone preamplifiers and sensor signal conditioning where signal integrity is critical.

Does BC558B_J35Z support Pb-free and RoHS-compliant manufacturing?

Yes - BC558B_J35Z is explicitly stated in the onsemi datasheet as Pb-free, halogen-free/BFR-free, and RoHS compliant. It meets the requirements of Directive 2011/65/EU and is suitable for use in consumer, industrial, and medical electronics where environmental compliance is mandatory. The TO-92−3 package uses lead-free molding compound and termination finishes, verified per JEDEC J-STD-020 and J-STD-006 standards.

What is the DC current gain (h_FE) range for BC558B_J35Z and how is it classified?

The BC558B_J35Z belongs to the "B" h_FE classification, with a guaranteed DC current gain range of 200–450 at V_CE = −5 V and I_C = −2 mA. This classification is laser-trimmed during manufacturing and marked as "B" on the device body. Designers can rely on this range for accurate base resistor calculations in both linear amplification and saturated switching applications without needing binning or post-test screening.