onsemi BC548B_J35Z

Overview

BC548B_J35Z from ON Semiconductor is an NPN epitaxial silicon transistor designed for general-purpose amplification and switching in low-power analog and digital circuits, with h_FE 200–450 at I_C = 2 mA, V_CEO = 30 V, and P_C = 500 mW in TO-92 package. It operates reliably across industrial temperature range (−65 °C to +150 °C) and supports audio preamplifier, sensor interface, and logic-level translation applications.

For engineers reviewing the BC548B_J35Z datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain classification (Class B), V_CE(sat) ≤ 250 mV at I_C = 10 mA/I_B = 0.5 mA, noise figure ≤ 10 dB at 1 kHz, f_T = 300 MHz, and TO-92 mechanical compatibility with legacy BC-series designs.

Technical Context

This device belongs to the BC546–BC550 family of through-hole NPN transistors standardized under JEDEC TO-92. Its epitaxial base construction enables stable h_FE across temperature and consistent V_BE(on) (580–700 mV) at I_C = 2 mA, supporting predictable biasing in discrete amplifier stages.

It features low output capacitance (C_ob = 3.5–6.0 pF at V_CB = 10 V) and input capacitance (C_ib = 9 pF), enabling use in RF-coupled preamp inputs up to ~30 MHz. The 30 V V_CEO rating targets 24 V rail systems and automotive body electronics where overvoltage margin is required beyond 12 V nominal.

Key Specifications

Pinout & Package

BC548B_J35Z is housed in a standard JEDEC TO-92 plastic package with straight leads (bulk packing variant). Pin identification follows conventional emitter-down orientation when flat side faces viewer and leads point downward: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC547B and 2N3904, BC548B_J35Z provides the narrowest noise figure range (2.0–10.0 dB) and tightest h_FE bin (200–450) within the BC-family, making it preferred for audio and precision analog gain stages where consistency matters more than maximum voltage rating.

Availability

BC548B_J35Z is available at Aetrix Electronics and suitable for audio preamplifier circuits, sensor signal conditioning modules, and LED driver switches requiring stable component supply across long-lifecycle industrial programs.

Supply support for BC548B_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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power and signal management solutions, with roots in Fairchild Semiconductor's discrete transistor legacy.

BC548B_J35Z belongs to the BC546–BC550 family-designed for cost-effective, high-reliability general-purpose amplification and switching in consumer, industrial, and automotive electronics.

FAQ

What is the absolute maximum collector-emitter voltage for BC548B_J35Z?

The absolute maximum V_CEO for BC548B_J35Z is 30 V at T_A = 25 °C. This rating applies to continuous DC operation; transient spikes must remain within this limit to prevent junction breakdown. Derating is required above 25 °C ambient, following the datasheet's thermal resistance curve. BC548B_J35Z must not be used in circuits where sustained V_CE exceeds 30 V, even briefly, unless externally clamped.

How does BC548B_J35Z differ from BC548C in terms of DC current gain?

BC548B_J35Z has an h_FE range of 200–450 at V_CE = 5 V and I_C = 2 mA, while BC548C is rated 420–800 under identical conditions. This means BC548B_J35Z offers tighter mid-range gain consistency ideal for predictable biasing, whereas BC548C targets higher-gain applications like low-input-current amplifiers. Both share identical package, pinout, and voltage ratings.

Is BC548B_J35Z suitable for low-noise audio applications?

Yes-BC548B_J35Z has a noise figure of 2.0–10.0 dB at V_CE = 5 V, I_C = 200 μA, and f = 1 kHz, placing it among the lower-noise variants in the BC546–BC550 series. Its performance is validated for electret microphone preamplifiers and line-level signal buffering where SNR >60 dB is required. For ultra-low-noise needs (<1.5 dB), BC549B or BC550C are better matched.

What is the recommended base resistor value for switching a 20 mA LED with BC548B_J35Z?

For reliable saturation with I_C = 20 mA, use I_B ≥ 1 mA (forced β = 20). With V_BE(sat) ≈ 700 mV and a 3.3 V GPIO drive, R_B = (3.3 V − 0.7 V) / 1 mA = 2.6 kΩ - a standard 2.7 kΩ resistor is appropriate. This ensures V_CE(sat) stays ≤250 mV, minimizing power loss. BC548B_J35Z supports this continuously without thermal runaway.

Does BC548B_J35Z have the same pinout as BC547B and BC546A?

Yes-BC548B_J35Z uses the standard TO-92 pinout: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter, matching all members of the BC546–BC550 family including BC547B and BC546A. Mechanical compatibility is confirmed by JEDEC TO-92 specification compliance and identical leadform drawings in the datasheet. No PCB layout change is needed when substituting within this family.