2N4449

Series:	--
Packaging:	Bulk
Part Status:	Active
Transistor Type:	NPN
Voltage - Collector Emitter Breakdown (Max):	20V
Vce Saturation (Max) @ Ib, Ic:	450mV @ 10mA, 100mA
Current - Collector Cutoff (Max):	400nA
DC Current Gain (hFE) (Min) @ Ic, Vce:	20 @ 100mA, 1V
Power - Max:	360mW
Frequency - Transition:	--
Operating Temperature:	-65°C ~ 200°C (TJ)
Mounting Type:	Through Hole
Package / Case:	TO-206AB, TO-46-3 Metal Can
Supplier Device Package:	TO-46 (TO-206AB)

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2N4449 Application Field and Working Principle

Introduction

The 2N4449 is a bipolar junction transistor (BJT) device manufactured by ON Semi. It is a small signal PNP transistor that is used for a variety of switching and general purpose applications. Its wide operating voltage range, high gain, and low noise make it suitable for use in audio, high gain and RF applications. This article will give an overview of the 2N4449’s application field and its working principle.

Applications

The 2N4449 is a bipolar NPN transistor available in TO-92 packages, and is used in a variety of applications such as audio amplifiers, high-gain radio-frequency amplifiers, low noise preamps, switching circuits, and push-pull amplifiers.The 2N4449 is suitable for use in audio amplifiers as it has good power ratings, low noise operation and good input and output characteristics. The small signal gain of the 2N4449 is also suitable for use in push-pull and bridge amplifiers, and its breakdown voltage of 30 volts makes it suitable for low frequency signal amplifiers.The 2N4449 is also appropriate for high gain radio-frequency amplifiers, as the small signal gain is high enough to make high-gain amplifiers. Additionally, the low noise characteristics of the device makes it suitable for low noise pre-amplifiers in radio receivers.The 2N4449 is also ideal for use in switching circuits as its high current handling capacity makes it suitable for switching applications. Additionally, the gain of the device is high enough to enable the device to be used in a wide range of device switching applications, such as relay control, logic level conversion, and solenoid control.

Working Principle

The 2N4449 is a three-terminal BJT, comprising of a base, emitter and collector. The base of the device is forward biased using a positive voltage, which allow electrons to flow from emitter to collector, thus enabling current to pass through the device.When the base is forward biased with a positive voltage, a small signal current will flow from the base to the emitter. This signal current is amplified by the transistor to produce a much larger current from the collector to the emitter. The ratio of the collector current to the base current is known as the current gain or gain of the device and is usually represented by the symbol "hfe".The 2N4449 can also be used as a switch with the base being driven directly to ground. When the base voltage is equal to or less than the collector voltage, the transistor is off and no current will flow between the collector and emitter. When the base voltage is greater than the collector voltage, the transistor turns on and current will continue to flow until the base voltage is reduced to less than the collector voltage, when the transistor turns off.

Conclusion

The 2N4449 is a small signal PNP transistor manufactured by ON Semi. It is suitable for use in audio, high gain and RF applications, as well as in switching circuits and logic level conversions. Its wide operating voltage range, high gain, and low noise characteristics make it ideal for a variety of applications, and its three-terminal design allows for easy and efficient operation. Furthermore, the gain of the device allows it to be used in a wide range of applications, making it a versatile and useful device.

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