onsemi KSC945GTA

Overview

KSC945GTA from ON Semiconductor is an NPN epitaxial silicon transistor designed for audio frequency amplification and high-frequency oscillator circuits, with a collector-base voltage rating of 60 V, DC current gain (hFE) up to 700 at IC = 1.0 mA, and a current gain bandwidth product (fT) of 300 MHz. It operates in TO-92 3L package with emitter-base breakdown voltage of 5 V and maximum collector current of 150 mA.

For engineers reviewing the KSC945GTA datasheet, pinout, applications, or equivalent options, key selection criteria include its fT = 300 MHz performance, hFE classification range (350–700 for 'G' grade), VCEO = 50 V rating, low VCE(sat) ≤ 0.30 V at IC = 100 mA/IB = 10 mA, and suitability for low-noise small-signal amplification where Cob = 2.5 pF and NF = 4.0 dB at 1 kHz.

Technical Context

This device is a general-purpose NPN bipolar junction transistor optimized for linear amplification and RF oscillator use in the <100 MHz range. Its epitaxial base construction enables high fT and stable hFE across bias conditions, while the TO-92 3L package supports through-hole prototyping and cost-sensitive consumer-grade designs.

The KSC945GTA belongs to the KSC945 family with center-collector pinout (Pin 1: Emitter, Pin 2: Base, Pin 3: Collector) and is complementary to the PNP KSA733. It exhibits low noise figure (4.0 dB), tight saturation voltage control (VCE(sat) ≤ 0.30 V), and thermal resistance RθJA = 500 °C/W under standard FR-4 PCB conditions.

Key Specifications

Pinout & Package

Package: TO-92 3L, molded plastic case with center-collector pin configuration (suffix "-C" per datasheet). Standard lead finish is matte tin.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2N3904 and BC547C, the KSC945GTA offers superior VCEO margin (50 V), lowest Cob (2.5 pF), and guaranteed G-grade hFE (350–700), making it especially well-suited for compact RF oscillator designs and low-noise audio preamps where both voltage headroom and capacitive loading are critical.

Availability

KSC945GTA is available at Aetrix Electronics and suitable for audio pre-amplifier stages, RF local oscillators, low-power DC motor drivers, and logic-level translation circuits requiring stable component supply and consistent hFE grading.

Supply support for KSC945GTA 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 connectivity solutions for automotive, industrial, cloud, medical, and consumer markets.

The KSC945GTA belongs to ON Semiconductor's legacy small-signal transistor portfolio, originally developed by Fairchild and optimized for cost-sensitive, high-volume analog signal conditioning and switching applications.

FAQ

What is the pin configuration of the KSC945GTA?

The KSC945GTA uses a TO-92 3L package with center-collector pinout: Pin 1 is Emitter, Pin 2 is Base, and Pin 3 is Collector. This configuration is confirmed in the official ON Semiconductor datasheet Rev. 1.1.0 and matches the "-C" suffix designation indicating center-collector orientation. The KSC945GTA must be mounted accordingly to avoid functional failure in circuit operation.

What does the "G" suffix in KSC945GTA indicate?

Per the KSC945 datasheet, the "G" suffix denotes the hFE classification grade: 350–700 at VCE = 6 V and IC = 1.0 mA. This is the highest gain bin offered for the KSC945GTA, ensuring predictable bias stability in amplifier designs where gain consistency is critical. The KSC945GTA is not interchangeable with lower-grade variants like KSC945YTA (hFE 40–80) without circuit revalidation.

Is the KSC945GTA suitable for RF oscillator applications?

Yes, the KSC945GTA is explicitly rated for high-frequency oscillator use with fT = 300 MHz and Cob = 2.5 pF, enabling stable operation in Colpitts or Hartley oscillator topologies up to ~100 MHz. Its low noise figure (4.0 dB) and tight VCE(sat) also support clean waveform generation. The KSC945GTA has been validated in FM receiver LO stages and low-power VHF transmitter modulator circuits.

How does the KSC945GTA compare to the 2N3904 in terms of voltage ratings?

The KSC945GTA has higher voltage ratings than the 2N3904: VCEO = 50 V vs. 40 V, and VCBO = 60 V vs. 60 V (equal). This 10 V advantage in collector-emitter breakdown allows the KSC945GTA to operate safely with higher supply rails in amplifier or switching applications. The KSC945GTA thus extends design margin in battery-powered or unregulated supply environments where transient spikes may occur.

Can the KSC945GTA replace the KSC945YTA in an existing design?

Yes, the KSC945GTA can replace the KSC945YTA only if the circuit relies on high hFE (350–700 vs. 40–80) for proper biasing-such as in emitter-follower buffers or high-gain preamps. However, in fixed-current-switching applications, the higher hFE may cause excessive base current draw or unintended saturation. Verify operating point stability and thermal performance before substituting KSC945GTA for KSC945YTA in any production design.