onsemi BC557_J35Z

Overview

BC557_J35Z from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and low-noise amplification in low-power analog and digital circuits. It features V_CEO = −45 V, I_C = −100 mA, h_FE range of 110–800 (depending on grade), f_T = 150 MHz, and TO-92-3 package with collector-base-emitter pinout. It serves as a complement to BC547/BC548 NPN transistors in dual-polarity bias networks.

For engineers reviewing the BC557_J35Z datasheet, pinout, applications, or equivalent options, key selection criteria include its −45 V V_CEO, low-noise performance (NF = 2–10 dB at 1 kHz), DC current gain classification (A/B/C), saturation voltage behavior under −10 mA/−100 mA loads, and TO-92 mechanical compatibility across legacy designs.

Technical Context

The BC557_J35Z operates as a medium-voltage, medium-current PNP bipolar junction transistor optimized for linear amplification and saturated switching. Its h_FE classification (e.g., A/B/C) directly determines small-signal gain consistency at I_C = −2 mA and V_CE = −5 V, while V_CE(sat) values (−90 mV to −650 mV) define on-state efficiency in switch-mode operation.

Thermal design relies on R_JA = 250 °C/W (FR-4 PCB, 76 mm × 114 mm), with derating of 4.0 mW/°C above 25°C and T_J max = 150°C. Its Cob = 6 pF at V_CB = −10 V enables stable high-frequency response up to 150 MHz in common-emitter configurations.

Key Specifications

Pinout & Package

BC557_J35Z is housed in a TO-92-3 plastic package (case 135AR), with standardized leadform: lead 1 = Collector, lead 2 = Base, lead 3 = Emitter. Dimensions are 4.83 mm × 4.76 mm × 3.6 mm (L × W × H), compatible with manual soldering and wave-reflow processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC557_J35Z, BC557BTA offers identical performance with standardized packaging logistics, while BC558BTA trades −45 V robustness for cost reduction in low-voltage designs-making BC557_J35Z the optimal choice for industrial 24 V systems requiring margin and noise-sensitive amplification.

Availability

BC557_J35Z is available at Aetrix Electronics and suitable for industrial sensor interfaces, discrete audio preamplifiers, and LED indicator driver circuits requiring stable component supply, consistent h_FE grading, and RoHS-compliant TO-92 packaging.

Supply support for BC557_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 manufacturer specializing in energy-efficient power management, analog, and sensing solutions for automotive, industrial, and cloud infrastructure markets.

The BC557_J35Z belongs to onsemi's legacy BC5xx PNP/NPN transistor family, engineered for cost-effective, reliable discrete amplification and switching in high-volume consumer, industrial, and automotive electronics.

FAQ

What is the maximum collector-emitter voltage rating for BC557_J35Z?

The BC557_J35Z has a guaranteed V_CEO rating of −45 V at T_A = 25°C. This means it can safely block up to 45 V in reverse polarity between collector and emitter without breakdown. Operation beyond this value risks permanent damage, especially under elevated temperature or pulsed conditions. Always apply ≥20% derating for reliability in production designs using BC557_J35Z.

Does BC557_J35Z have a specified noise figure, and how does it vary by grade?

Yes, BC557_J35Z has a documented noise figure: 2–10 dB at 1 kHz, V_CE = −5 V, I_C = −200 µA, and R_G = 2 kΩ. Lower values (e.g., 2–4 dB) correspond to higher h_FE grades (B/C), while grade A typically exhibits 5–10 dB. This makes BC557_J35Z suitable for low-noise preamplifier stages where signal integrity is critical, especially when binned to B or C grade.

What is the pin configuration of BC557_J35Z in its TO-92 package?

BC557_J35Z uses the standard TO-92-3 (case 135AR) pinout: viewed from the flat side with leads pointing downward, left-to-right is Collector (pin 1), Base (pin 2), Emitter (pin 3). This matches all BC556–BC560 variants and ensures mechanical and electrical compatibility with existing PCB footprints designed for this family.

Can BC557_J35Z replace BC557BTA in existing designs?

Yes, BC557_J35Z is functionally and electrically identical to BC557BTA-same V_CEO, h_FE grading, f_T, package (TO-92-3, case 135AR), and RoHS compliance. The "J35Z" suffix reflects a specific distribution channel or internal lot coding, not a parametric deviation. No layout or schematic changes are needed when substituting BC557_J35Z for BC557BTA.

What thermal derating applies to BC557_J35Z above 25°C ambient?

BC557_J35Z has a thermal resistance R_JA = 250 °C/W on a standard FR-4 PCB (76 mm × 114 mm). Its power dissipation must be derated linearly at 4.0 mW/°C above 25°C ambient. For example, at 75°C ambient, maximum allowable P_D = 500 mW − (4.0 mW/°C × 50°C) = 300 mW. Exceeding this risks junction temperature exceeding 150°C and device failure.