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Understanding the KSC1845 Transistor

The KSC1845 is a low-noise NPN transistor designed for audio and other sensitive electronic applications. This article explores its features, usage, and common applications, making it easy to understand how it fits into various circuits.

Catalog

KSC1845 Product Overview

The KSC1845 belongs to the NPN transistor family, specifically designed to handle audio-frequency applications with low noise, making it ideal for sound-sensitive electronic circuits. Its silicon-based TO-92 package provides durability and a compact design for easy integration.

The KSC1845 has three main terminals: the base, collector, and emitter, each playing a role in directing current flow. When a current flows through the base, the transistor opens the path between the collector and emitter, allowing a controlled flow of current. This feature allows it to amplify signals, with the three-layer structure (two n-doped layers and one p-doped) forming a reliable switch. With its low-noise performance, it is a preferred choice for audio amplification and other sensitive applications.

KSC1845 Pin Configuration

KSC1845 CAD Model

KSC1845 Symbol

KSC1845 Footprint

KSC1845 3D Model

KSC1845 Features

Audio Frequency Low-Noise Amplifier

The KSC1845 is designed to deliver clear audio amplification with minimal noise, making it a good choice for sensitive audio applications. This low-noise feature helps maintain sound quality, especially in circuits where clear signal transmission is needed.

Complement to KSA992

This transistor is often used as a counterpart to the KSA992, an NPN transistor that complements the KSC1845 in many circuits. When paired, they work well together, enhancing performance in a variety of electronic applications.

Applications of KSC1845

Audio Circuits

The low-noise quality of the KSC1845 makes it ideal for audio circuits, where it amplifies signals without adding unwanted background noise, ensuring better sound clarity in audio equipment.

High-Frequency Power Conversion

In power conversion circuits, this transistor supports high-frequency operations, providing efficient power handling in electronic systems that require stable and smooth conversion.

Electronic Ballasts

KSC1845 is also used in electronic ballasts, which regulate current in lighting systems, especially in energy-efficient bulbs. Its stability makes it suitable for these types of circuits.

Voltage Regulation Circuits

This transistor is commonly used in voltage regulation circuits to help maintain steady voltage levels, ensuring consistent performance in various electronic devices.

Power Amplifiers

In power amplification applications, the KSC1845 helps increase the strength of weak signals, making it useful in audio and other low-power signal applications.

Multivibrators

This transistor can be used in both bistable and astable multivibrator circuits, which are essential for creating switching and timing signals in many electronic devices.

Energy-Saving Lighting

It is used in circuits for energy-saving lighting, where it assists in controlling power usage effectively, especially in lights that need to be both efficient and durable.

Low Power Load Support

KSC1845 can support loads under 0.05A, making it suitable for applications requiring low power consumption, contributing to the efficiency of the circuit.

Switching Power Supplies

The transistor is often used in high-switching power supply systems, where it helps manage rapid changes in voltage and current, providing stable performance in these demanding applications.

KSC1845 Specifications

Technical specifications, features, characteristics, and components with comparable specifications to ON Semiconductor KSC1845FTA.

Type	Parameter
Factory Lead Time	6 Weeks
Contact Plating	Tin
Mount	Through Hole
Mounting Type	Through Hole
Package / Case	TO-226-3, TO-92-3 (TO-226AA) (Formed Leads)
Number of Pins	3
Weight	240mg
Transistor Element Material	Silicon
Collector-Emitter Breakdown Voltage	120V
Number of Elements	1
hFE Min	200
Operating Temperature	150°C TJ
Packaging	Tape & Box (TB)
Published	2002
JESD-609 Code	e3
Pbfree Code	Yes
Part Status	Active
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Number of Terminations	3
ECCN Code	EAR99
Voltage - Rated DC	120V
Max Power Dissipation	500mW
Terminal Position	Bottom
Current Rating	50mA
Frequency	110MHz
Base Part Number	KSC1845
Element Configuration	Single
Power Dissipation	500mW
Transistor Application	Amplifier
Gain Bandwidth Product	110MHz
Polarity/Channel Type	NPN
Transistor Type	NPN
Collector Emitter Voltage (VCEO)	120V
Max Collector Current	50mA
DC Current Gain (hFE) (Min) @ Ic, Vce	300 @ 1mA 6V
Current - Collector Cutoff (Max)	50nA ICBO
Vce Saturation (Max) @ Ib, Ic	300mV @ 1mA, 10mA
Transition Frequency	110MHz
Max Breakdown Voltage	120V
Collector Base Voltage (VCBO)	120V
Emitter Base Voltage (VEBO)	5V
Height	4.58mm
Length	4.58mm
Width	3.86mm
REACH SVHC	No SVHC
Radiation Hardening	No
RoHS Status	ROHS3 Compliant
Lead Free	Lead Free

Similar Parts to KSC1845

The parts on the right have specifications similar to ON Semiconductor KSC1845FTA

Part Number	Manufacturer	Mount	Package / Case	Collector Emitter Breakdown Voltage	Max Collector Current	Transition Frequency	Collector Emitter Saturation Voltage	hFE Min	Max Power Dissipation
KSC1845PTA	ON Semiconductor	Through Hole	TO-226-3, TO-92-3 (TO-226AA)	120 V	50 mA	110 MHz	70 mV	200	500 mW
2N5550TFR	ON Semiconductor	Through Hole	TO-226-3, TO-92-3 (TO-226AA)	140 V	600 mA	100 MHz	250 mV	60	625 mW
KSC1845PTA	ON Semiconductor	Through Hole	TO-226-3, TO-92-3 (TO-226AA)	140 V	600 mA	100 MHz	250 mV	60	625 mW
2N5550TA	ON Semiconductor	Through Hole	TO-226-3, TO-92-3 (TO-226AA)	120 V	50 mA	-	70 mV	200	500 mW

Equivalent Options for KSC1845

• FJV1845

Usage Guidelines for KSC1845

The KSC1845 transistor is activated primarily through the base terminal. When a voltage is applied to this terminal, it triggers the transistor, allowing current to move from the collector to the emitter. This controlled flow makes it effective for amplifying signals in a circuit.

Due to its design, the KSC1845 lacks symmetry. If you swap the emitter and collector, the transistor won’t work in its usual active mode but will instead operate in reverse. This behavior results from the specific doping levels in each terminal, making correct orientation essential for proper function.

KSC1845 Package Details

Manufacturer Information for KSC1845

On Semiconductor (Nasdaq: ON) manufactures the KSC1845, focusing on technology that conserves energy while providing reliable power and signal management. With a broad lineup of products, the company serves various industries and aims to meet the growing demand for efficiency in electronics. ON Semiconductor has established itself globally, operating through a network of facilities and sales offices across North America, Europe, and the Asia Pacific. Through these centers, the company ensures that products like the KSC1845 meet quality standards and deliver dependable performance for applications worldwide.

Datasheet PDF

KSC1845FTA Datasheet:

KSC1845FTA.pdf