onsemi KSC945CGBU

Overview

KSC945CGBU from ON Semiconductor is an NPN epitaxial silicon transistor optimized for audio-frequency amplification and high-frequency oscillator circuits, with a 60 V collector-base breakdown voltage (VCBO), 300 MHz current gain bandwidth product (fT), and 150 mA maximum collector current (IC), commonly deployed in portable audio preamplifiers and RF signal generators.

For engineers reviewing the KSC945CGBU datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92 3L package, center-collector pinout (Emitter–Collector–Base), DC current gain range of 200–400 (Class G), and low noise figure of 4.0 dB at 1 kHz - all critical for low-distortion analog signal paths.

Technical Context

This discrete NPN bipolar junction transistor uses epitaxial base construction to achieve high fT and stable hFE across operating conditions. Its 500 °C/W junction-to-ambient thermal resistance and 250 mW power dissipation rating reflect design for low-power, through-hole mounted linear applications without forced cooling.

The device operates with fixed bias or emitter-degenerated configurations, supporting VCE = 6 V test conditions for hFE and fT characterization. Its 2.5 pF output capacitance (Cob) and 0.15–0.30 V VCE(sat) at IC = 100 mA / IB = 10 mA enable efficient switching and analog gain stages up to ~100 MHz.

Key Specifications

Pinout & Package

Package: TO-92 3L, molded plastic case with center-collector configuration (Pin 1: Emitter, Pin 2: Collector, Pin 3: Base).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2N3904 and BC547C, the KSC945CGBU delivers superior RF capability via lower Cob and guaranteed 300 MHz fT, while its center-collector pinout and 4.0 dB noise figure make it uniquely suited for space-constrained, low-noise analog designs where layout reuse is critical.

Availability

KSC945CGBU is available at Aetrix Electronics and suitable for portable audio preamplifiers, RF local oscillators, and DC motor speed controllers requiring stable component supply, long-term obsolescence management, and traceable sourcing.

Supply support for KSC945CGBU 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, analog, sensor, and logic solutions for automotive, industrial, cloud computing, and consumer markets.

The KSC945CGBU belongs to ON Semiconductor's legacy small-signal transistor portfolio, originally developed by Fairchild for cost-sensitive, high-reliability analog signal conditioning and RF generation in mass-produced electronics.

FAQ

What is the pin configuration of the KSC945CGBU?

The KSC945CGBU uses a TO-92 3L package with center-collector pinout: Pin 1 is Emitter, Pin 2 is Collector, and Pin 3 is Base. This differs from standard E-B-C orientation, so PCB layout must match the "C" suffix designation. The KSC945CGBU datasheet confirms this arrangement under the "Suffix '-C' means Center Collector" note.

What does the 'G' in KSC945CGBU indicate?

The 'G' in KSC945CGBU denotes hFE classification Group G (200–400), per the official KSC945 Rev. 1.1.0 datasheet. This binning ensures tighter DC current gain consistency for bias-critical amplifier designs. The KSC945CGBU is not interchangeable with Y-, O-, or R-class variants without verifying circuit stability under gain variation.

Is the KSC945CGBU suitable for RF oscillator applications?

Yes - the KSC945CGBU is explicitly rated for high-frequency oscillator use, with a typical fT of 300 MHz and Cob of 2.5 pF. These parameters support stable operation in Colpitts and Hartley oscillator topologies up to 100 MHz. The KSC945CGBU's low noise figure further enhances spectral purity in local oscillator stages.

How does the KSC945CGBU compare to the complementary PNP KSA733?

The KSC945CGBU and KSA733 form a matched NPN/PNP pair with symmetrical voltage ratings (VCBO = 60 V / VCEO = 50 V) and compatible hFE ranges. They are designed for push-pull, differential, or complementary-symmetry circuits. The KSC945CGBU's 300 MHz fT exceeds the KSA733's 200 MHz, making it preferred for higher-frequency NPN-side roles.

What is the maximum power dissipation of the KSC945CGBU?

The KSC945CGBU has a maximum power dissipation of 250 mW at TA = 25°C, derating linearly by 2.0 mW/°C above that temperature. This rating assumes standard FR-4 PCB mounting (76 mm × 114 mm) with minimum land pattern. Exceeding this limit risks thermal runaway; the KSC945CGBU junction temperature must remain below 150°C.