onsemi BC558C_J35Z

Overview

BC558C_J35Z from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and linear amplification in low-power analog and digital circuits, with V_CEO = −30 V, I_C = −100 mA, h_FE = 420–800 (Class C), and TO-92-3 (Case 135AR) package. It serves as a complement to BC546–BC550 NPN devices in push-pull stages, bias networks, and signal conditioning blocks.

For engineers reviewing the BC558C_J35Z datasheet, pinout, applications, or equivalent options, key selection considerations include its −30 V V_CEO rating, Class C h_FE range, low-noise capability (NF = 2–10 dB at 1 kHz), TO-92 leadform compatibility, and RoHS-compliant Pb-free construction.

Technical Context

The BC558C_J35Z operates as a medium-gain, low-voltage PNP bipolar junction transistor optimized for DC-coupled amplification and saturated switching. Its h_FE classification (C: 420–800) ensures consistent current gain across production lots under V_CE = −5 V and I_C = −2 mA conditions, while its −30 V V_CEO and −30 V V_CBO ratings define safe operation in low-to-moderate voltage rail applications.

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. The device exhibits f_T = 150 MHz at V_CE = −5 V, I_C = −10 mA, enabling use in audio-frequency amplifiers and low-speed digital interfaces.

Key Specifications

Pinout & Package

BC558C_J35Z is housed in a TO-92-3 plastic package (Case 135AR), with leads formed for through-hole mounting. Pin identification follows standard orientation: flat side facing viewer, leads down, left-to-right = Collector (1), Base (2), Emitter (3).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC558B and BC557C, BC558C_J35Z delivers the highest h_FE consistency within the BC55x family while maintaining the lowest V_CEO rating-making it optimal for compact, low-voltage, high-gain analog stages where voltage headroom is constrained.

Availability

BC558C_J35Z is available at Aetrix Electronics and suitable for audio preamplifier design, discrete logic level translation, and LED segment driving applications requiring stable component supply, long-term obsolescence management, and RoHS-compliant sourcing.

Supply support for BC558C_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 specializing in energy-efficient power and sensing solutions for automotive, industrial, cloud computing, and consumer electronics markets.

The BC558C_J35Z belongs to onsemi's legacy BC55x PNP transistor family, engineered for reliability and consistency in general-purpose analog and switching functions across commercial and industrial temperature ranges.

FAQ

What is the maximum continuous collector current rating for BC558C_J35Z?

The BC558C_J35Z has a maximum continuous collector current (I_C) rating of −100 mA at T_A = 25 °C. This value decreases with rising ambient temperature due to its 4.0 mW/°C thermal derating slope, requiring appropriate PCB copper area or forced-air cooling for sustained operation near this limit. The BC558C_J35Z must not exceed this rating to avoid permanent degradation of h_FE or thermal runaway.

Is BC558C_J35Z pin-compatible with BC557 or BC559 variants?

Yes, BC558C_J35Z shares identical TO-92-3 (Case 135AR) mechanical packaging and pinout (Collector-Base-Emitter, left-to-right with flat side facing) with BC557, BC559, and other BC55x series transistors. However, electrical differences-including V_CEO (−30 V vs. −45 V or −65 V), h_FE class, and noise figure-require verification against circuit requirements before substitution. The BC558C_J35Z is not a drop-in replacement without functional validation.

What does the 'C' suffix in BC558C_J35Z indicate?

The 'C' in BC558C_J35Z denotes h_FE classification per onsemi's datasheet: Class C corresponds to a DC current gain range of 420–800 at V_CE = −5 V and I_C = −2 mA. This binning ensures predictable gain behavior in production assemblies, reducing calibration effort in amplifier and current-source designs that rely on stable h_FE. The BC558C_J35Z is selected specifically for high-gain, low-variance applications.

Does BC558C_J35Z support low-noise audio applications?

Yes, BC558C_J35Z is specified for low-noise operation with a noise figure (NF) of 2–10 dB at 1 kHz, V_CE = −5 V, and I_C = −200 µA-matching the BC556/557/558 group's noise performance. This makes the BC558C_J35Z suitable for first-stage preamplifiers in condenser microphones, instrumentation front-ends, and other sensitive analog signal paths where input-referred noise must remain below 10 nV/√Hz.

What is the thermal resistance junction-to-ambient for BC558C_J35Z?

The BC558C_J35Z has a thermal resistance junction-to-ambient (R_JA) of 250 °C/W under standard FR-4 PCB conditions (76 mm × 114 mm, minimum land pattern). This value assumes natural convection cooling; actual R_JA improves with larger copper pours or forced airflow. For reliable operation at full 500 mW dissipation, ambient temperature must remain below 25 °C-or derated accordingly using the 4.0 mW/°C slope. The BC558C_J35Z thermal profile is fully defined in onsemi's datasheet Figure 8.