onsemi KSC2785YTA

Overview

KSC2785YTA from ON Semiconductor (formerly Fairchild) is an NPN epitaxial silicon transistor designed for audio frequency amplification and high-frequency oscillator circuits, with VCBO=60 V, VCEO=50 V, IC=150 mA, hFE=200–400 (Y-class), and fT=300 MHz.

For engineers reviewing the KSC2785YTA datasheet, pinout, applications, or equivalent options, this device supports low-noise analog gain stages, RF oscillator biasing, and complementary switching with KSA1175 in push-pull configurations under 50 V supply rails.

Technical Context

This NPN transistor operates in linear active mode for small-signal amplification and saturation/cutoff for switching, with guaranteed hFE classification Y (200–400) at VCE=6 V and IC=1.0 mA. Its 300 MHz fT enables stable operation up to VHF band oscillators.

Designed for TO-92S package mounting, it features low Cob=2.5 pF at VCB=6 V and f=1 MHz, low VCE(sat)=0.15–0.3 V at IC=100 mA/IB=10 mA, and NF=4.0 dB at f=1 kHz with RS=500 Ω - confirming suitability for low-distortion audio preamplifiers.

Key Specifications

Pinout & Package

Package: TO-92S - compact through-hole plastic package with 1.27 mm lead pitch, 3.72 mm body height, and 2.86 mm width; optimized for manual assembly and board-level thermal dissipation up to 250 mW.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC547C and MPSA18, the KSC2785YTA offers factory-binned Y-class hFE (200–400), guaranteed 50 V VCEO rating, and low 2.5 pF Cob - making it preferred for production-audio circuits where gain predictability and rail margin are critical.

Availability

KSC2785YTA is available at Aetrix Electronics and suitable for audio preamplifiers, RF oscillator modules, push-pull driver stages, and low-voltage switch interfaces requiring stable component supply and long-term obsolescence management.

Supply support for KSC2785YTA 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 supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The KSC2785YTA belongs to Fairchild's legacy small-signal bipolar transistor family, engineered specifically for high-fidelity audio amplification and stable RF oscillator operation in cost-sensitive consumer and industrial equipment.

FAQ

What is the hFE range for KSC2785YTA?

The KSC2785YTA is binned to the Y-class hFE specification, guaranteeing a DC current gain of 200–400 when measured at VCE=6 V and IC=1.0 mA. This tight binning improves bias stability in production audio amplifier circuits compared to standard-grade variants like KSC2785O or KSC2785G.

Is KSC2785YTA pin-compatible with other TO-92S transistors?

Yes, the KSC2785YTA uses the standard TO-92S package with pinout E-C-B (Emitter–Collector–Base), matching industry-standard small-signal NPN transistors such as BC547 and MPSA18. Mechanical compatibility enables direct socket or PCB footprint reuse, though electrical parameters must be verified per application.

What is the maximum operating frequency supported by KSC2785YTA?

The KSC2785YTA has a current gain bandwidth product (fT) of 300 MHz, meaning it maintains usable current gain up to that frequency under specified test conditions (VCE=6 V, IC=10 mA). In practice, stable oscillator operation is achievable up to ~100 MHz with appropriate tank circuit design and layout control.

Can KSC2785YTA replace KSC2785O in existing designs?

Yes, the KSC2785YTA can replace KSC2785O in most applications, as both share identical absolute maximum ratings and package. However, KSC2785YTA's higher and narrower hFE range (200–400 vs. 70–140) may require minor bias resistor adjustment to maintain optimal Q-point in linear amplifier stages.

Does KSC2785YTA have a documented complementary PNP part?

Yes, the KSC2785YTA is explicitly documented as complementary to the KSA1175 PNP transistor in Fairchild's original datasheet. Both devices share matched voltage ratings, gain ranges, and TO-92S packaging - enabling balanced push-pull and differential pair implementations without custom matching.