onsemi KSC1815YBU

Overview

KSC1815YBU from ON Semiconductor (formerly Fairchild) is an NPN epitaxial silicon transistor designed for audio-frequency amplification and high-frequency oscillator circuits, with V_CBO = 60 V, V_CEO = 50 V, I_C = 150 mA, P_D = 400 mW, and f_T = 80 MHz - commonly used in low-noise preamplifier stages and local oscillator modules in consumer AM/FM radios.

For engineers reviewing the KSC1815YBU datasheet, pinout, applications, or equivalent options, key selection considerations include its h_FE classification (Y: 120–240 at I_C = 2 mA), low V_CE(sat) (0.10–0.25 V), noise figure (1.0–10.0 dB), TO-92 package thermal resistance (312 °C/W), and complementarity to KSA1015 PNP transistors in push-pull designs.

Technical Context

This discrete NPN bipolar junction transistor operates in linear and switching modes, featuring a 150 °C maximum junction temperature and 5 µA maximum leakage (I_CBO, I_EBO). Its f_T of 80 MHz supports stable operation up to VHF band oscillators when biased appropriately.

The device uses epitaxial base construction for improved gain consistency and low noise performance; Cob output capacitance (2.0–3.0 pF at V_CB = 10 V) enables predictable tuning in LC tank circuits, while V_BE(sat) = 1.0 V at I_C = 100 mA ensures reliable saturation in driver-stage applications.

Key Specifications

Pinout & Package

Package: TO-92 (3-lead plastic through-hole), lead material: tin-plated copper, body dimensions: 4.7 mm × 3.7 mm × 4.6 mm (L × W × H), standard JEDEC TO-92 outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2N3904 and BC547B, the KSC1815YBU offers optimized balance of f_T, noise, and saturation characteristics specifically validated for audio preamp and HF oscillator roles - making it preferable where low-noise gain and stable LC resonance are design-critical.

Availability

KSC1815YBU is available at Aetrix Electronics and suitable for AM/FM radio design, low-noise preamplifier development, and HF oscillator prototyping requiring stable component supply and long-term obsolescence management.

Supply support for KSC1815YBU 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 (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor components, specializing in power management, analog, sensors, and discrete devices.

The KSC1815YBU belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, originally developed for cost-sensitive, high-reliability consumer audio and RF signal conditioning applications.

FAQ

What is the pin configuration of the KSC1815YBU?

The KSC1815YBU uses a standard TO-92 package with pin 1 as Emitter, pin 2 as Collector, and pin 3 as Base - verified per Fairchild KSC1815 Rev. 1.8 datasheet and ON Semiconductor packaging documentation. This configuration is consistent across all KSC1815 variants including KSC1815YBU, and must be observed to avoid reverse-bias damage during circuit assembly.

What does the 'Y' suffix in KSC1815YBU indicate?

The 'Y' in KSC1815YBU denotes the h_FE classification grade: DC current gain of 120–240 at V_CE = 6 V and I_C = 2 mA. The 'BU' suffix indicates tape-and-reel packaging per Fairchild nomenclature; this grading and packaging are fully supported in ON Semiconductor's post-integration part numbering system.

Can KSC1815YBU replace KSC1815YTA in existing designs?

Yes - KSC1815YBU and KSC1815YTA share identical electrical specifications, TO-92 package, and pinout; the only difference is packaging method (bulk vs. ammo pack). No circuit or layout changes are needed when substituting KSC1815YBU for KSC1815YTA in production or repair scenarios.

Is KSC1815YBU suitable for switching applications?

Yes - KSC1815YBU supports switching use with V_CE(sat) = 0.10–0.25 V at I_C = 100 mA and I_B = 10 mA, and t_on/t_off performance adequate for ≤100 kHz digital signal routing. It is not recommended for high-frequency PWM (>500 kHz) due to f_T-limited gain roll-off and lack of specified switching timing parameters in the datasheet.

How does KSC1815YBU compare to KSA1015 in circuit design?

KSC1815YBU is the NPN complement to the PNP KSA1015, sharing matching V_CEO, I_C, P_D, and h_FE grading structure. They are intended for paired use in Class-B/AB amplifiers, differential inputs, and push-pull oscillator topologies - with KSC1815YBU handling positive half-cycles and KSA1015 negative half-cycles in symmetrical configurations.