onsemi BC308A_J35Z

Overview

BC308A_J35Z from Fairchild Semiconductor is a PNP epitaxial silicon transistor designed for low-noise amplifier and general-purpose switching applications, with V_CEO = −25 V, I_C = −100 mA, P_C = 500 mW, h_FE = 180–460 (Class B), and TO-92 package. It operates in audio preamplifier stages and relay driver circuits where moderate gain and low saturation voltage are required.

For engineers reviewing the BC308A_J35Z datasheet, pinout, applications, or equivalent options, key selection criteria include verified DC current gain range, collector-emitter breakdown voltage under specified test conditions, saturation voltage at defined drive levels, noise figure at 1 kHz, and TO-92 mechanical compatibility with legacy through-hole PCB layouts.

Technical Context

The BC308A_J35Z is a discrete PNP bipolar junction transistor optimized for linear amplification and switching in low-to-medium power analog circuits. Its Class B h_FE (180–460) ensures stable biasing in emitter-follower and common-emitter configurations, while f_T = 130 MHz supports audio-frequency signal integrity without high-frequency roll-off.

It features low V_CE(sat) (−0.5 V @ I_C = −10 mA, I_B = −0.5 mA) and V_BE(sat) (−0.7 V), enabling efficient operation in saturated-switching roles. The device's Cob = 6 pF and Cib = 12 pF support predictable frequency response in tuned amplifier stages.

Key Specifications

Pinout & Package

BC308A_J35Z is housed in a standard TO-92 plastic package with 3 leads, compatible with manual soldering and wave-solder processes. Lead spacing and body dimensions conform to JEDEC TO-92 outline (3.60 ±0.20 mm width, 4.58 +0.25/−0.15 mm height).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC308A_J35Z, BC327-40 offers greater voltage margin and tighter h_FE control for precision biasing, while PN2907A trades bandwidth and noise performance for broader availability and lower cost in non-audio applications.

Availability

BC308A_J35Z is available at Aetrix Electronics and suitable for audio preamplifier stages, relay driver circuits, and LED current sink applications requiring stable component supply and long-term obsolescence management.

Supply support for BC308A_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

Fairchild Semiconductor was a U.S.-based semiconductor manufacturer specializing in discrete power devices, analog ICs, and optoelectronics before its acquisition by ON Semiconductor in 2016.

The BC308A_J35Z belongs to the BC307/308/309 family of general-purpose PNP transistors engineered for cost-sensitive, through-hole-based analog and switching functions in consumer, industrial, and instrumentation equipment.

FAQ

What is the guaranteed h_FE range for BC308A_J35Z?

The BC308A_J35Z is classified as Class B, with a guaranteed DC current gain (h_FE) range of 180 to 460 when measured at V_CE = −5 V and I_C = −2 mA. This specification is confirmed in the Fairchild BC307/308/309 datasheet Rev. A2 and applies directly to the BC308A_J35Z variant. Designers should use the minimum value (180) for worst-case bias calculations in BC308A_J35Z circuits.

Does BC308A_J35Z support audio-frequency amplification?

Yes, BC308A_J35Z supports audio-frequency amplification up to 20 kHz with low distortion due to its 130 MHz f_T and 2 dB noise figure at 1 kHz. Its h_FE stability and low V_CE(sat) ensure clean signal swing in common-emitter preamp stages. The BC308A_J35Z is explicitly recommended for "low-noise" amplifier applications in its official datasheet.

What is the maximum continuous collector current for BC308A_J35Z?

The maximum continuous collector current (I_C) for BC308A_J35Z is −100 mA at T_A = 25°C, as specified in the Absolute Maximum Ratings table. Derating is required above 25°C ambient - approximately −0.83 mA/°C - to maintain safe junction temperature. This rating applies to steady-state DC operation, not pulsed conditions, in BC308A_J35Z designs.

Is BC308A_J35Z pin-compatible with BC307 or BC309?

Yes, BC308A_J35Z shares identical pinout (1: Collector, 2: Base, 3: Emitter) and TO-92 package dimensions with BC307 and BC309. All three devices follow the same JEDEC outline and lead assignment. However, electrical differences exist: BC307 has V_CEO = −45 V and BC309 has lower noise (4 dB at 30–15 kHz), so direct substitution requires verification of voltage and noise requirements in the BC308A_J35Z application.

What is the typical V_CE(sat) for BC308A_J35Z under standard switching conditions?

The typical V_CE(sat) for BC308A_J35Z is −0.5 V when tested at I_C = −10 mA and I_B = −0.5 mA, per the Electrical Characteristics table. At higher currents (I_C = −100 mA, I_B = −5 mA), it drops to −0.3 V. These values define conduction losses in BC308A_J35Z switching applications and inform thermal design margins.