onsemi BC546_J18Z

Overview

BC546_J18Z from ON Semiconductor is an NPN epitaxial silicon transistor designed for general-purpose switching and amplification in low-power analog and digital circuits. It features V_CEO = 65 V, I_C = 100 mA, P_C = 500 mW, h_FE range 110–800 (depending on grade), and TO-92 package - commonly used in signal conditioning stages of sensor interfaces and discrete logic level translators.

For engineers reviewing the BC546_J18Z datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain classification (A/B/C), saturation voltage at defined I_B/I_C, noise figure (especially for BC549/BC550 variants), and compatibility with legacy BC-series designs requiring V_CEO ≥ 65 V.

Technical Context

The BC546_J18Z belongs to the BC546–BC550 family of through-hole NPN transistors fabricated using epitaxial planar process technology. Its structure supports stable h_FE across temperature and bias, with specified V_CE(sat) ≤ 250 mV at I_C = 10 mA / I_B = 0.5 mA and f_T = 300 MHz under V_CE = 5 V, I_C = 10 mA conditions.

It operates within a junction temperature range of –65 °C to +150 °C and is rated for V_CBO = 80 V, making it suitable for moderate-voltage interface and driver applications where reliability under transient overvoltage is required. The device is not optimized for RF power amplification but supports broadband small-signal amplification up to ~100 MHz.

Key Specifications

Pinout & Package

BC546_J18Z is housed in a JEDEC TO-92 3-lead plastic package with straight leads (bulk or ammo packing). Standard pinout: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter - verified per Fairchild/ON Semiconductor mechanical drawings and electrical test configurations.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC547BTA and PN2222A, BC546_J18Z provides the highest V_CEO in the TO-92 form factor among standard BC-series transistors, enabling direct replacement in legacy 48 V telecom or automotive body-control modules without layout change or voltage derating.

Availability

BC546_J18Z is available at Aetrix Electronics and suitable for industrial control panels, audio signal chains, sensor interface boards, and discrete logic translation circuits requiring stable component supply across long-lifecycle embedded programs.

Supply support for BC546_J18Z 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC546_J18Z belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, originally developed by Fairchild and maintained for backward compatibility in cost-sensitive, high-reliability discrete designs.

FAQ

What is the maximum collector-emitter voltage rating for BC546_J18Z?

The BC546_J18Z has a guaranteed V_CEO rating of 65 V, verified per ON Semiconductor's absolute maximum ratings table. This value defines the upper limit of DC or peak repetitive voltage the transistor can block between collector and emitter with base open. Exceeding this voltage risks avalanche breakdown and permanent damage. Designers should apply derating (e.g., 80% of 65 V = 52 V) for reliability in variable-temperature environments.

Does BC546_J18Z have a specified h_FE grade, and how is it marked?

Yes, BC546_J18Z corresponds to the BC546 "A" grade with h_FE = 110–220 at V_CE = 5 V and I_C = 2 mA, as confirmed by Fairchild/ON Semiconductor datasheet classification tables. The "J18Z" suffix aligns with ON Semiconductor's post-integration marking convention for BC546A devices in TO-92 bulk packaging, replacing legacy underscore-based identifiers.

Can BC546_J18Z be used as a direct replacement for BC546B or BC546C in existing designs?

No - BC546_J18Z is functionally equivalent to BC546A (h_FE 110–220), not BC546B (200–450) or BC546C (420–800). Substituting it into circuits relying on higher gain may cause insufficient drive, unstable biasing, or failure to saturate. Always verify h_FE-dependent performance (e.g., switching speed, quiescent current) before interchange, even within the same BC546 family.

What is the thermal resistance junction-to-ambient (R_θJA) for BC546_J18Z in TO-92 package?

ON Semiconductor specifies R_θJA = 200 °C/W for the TO-92 package under standard JEDEC test conditions (single-layer PCB, 1 in² copper pad). This value assumes no added heatsinking and defines the temperature rise above ambient per watt of dissipated power. At its rated 500 mW, BC546_J18Z will rise ~100 °C above ambient - confirming need for adequate airflow or copper area in sustained high-current operation.

Is BC546_J18Z compliant with RoHS and REACH regulations?

Yes, BC546_J18Z is manufactured and shipped in full compliance with EU RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006, as documented in ON Semiconductor's material declarations and certificate of compliance. Lead-free (Pb-free) terminations and halogen-free molding compound are standard for all current production lots of this part.