2SC945 Transistor Datasheet, Applications and Equivalent IC

Introduction

The 2SC945 is a popular bipolar NPN transistor that is widely in use in electronic circuits. With its small size, high gain, and low noise characteristics, the 2SC945 has become a popular choice for amplifier, oscillator, and switching applications. This transistor design is to operate at a maximum collector-emitter voltage of 50V, with a maximum collector current of 150mA and power dissipation of 400mW. In this article, we will delve into the specifications and applications of the 2SC945 transistor, providing insights into how this device can be utilized to optimize electronic circuits.

Key Features of 2SC945 Transistor

• High hFE and good linearity
• Complementary to 2SA733
• Maximum ratings:
• Collector-Emitter Voltage: VCEO = 50V
• Collector-Base Voltage: VCBO = 60V
• Emitter-Base Voltage: VEBO = 5V
• Collector Current: IC = 150mA
• Power Dissipation: Pd = 400mW

Absolute Maximum Ratings of 2SC945

Parameter	Symbol	Rating	Unit
Collector-Base	VCBO	60	V
Collector-Emitter	VCEO	50	V
Emitter-Base	VEBO	5	V
Collector Current	IC	150	mA
Power Dissipation	Pd	400	mW
Junction Temp.	Tj	150	°C
Storage Temp.	Tstg	-55~150	°C

Electrical Characteristics (Ta=25°C unless otherwise specified)

Parameter	Symbol	Test Condition	Min.	Typ.	Max.	Unit
Collector Cut-off Current	ICBO	VCB=50V	–	–	100	nA
Emitter Cut-off Current	IEBO	VEB=5V	–	–	100	nA
DC Current Gain	hFE	VCE=6V, IC=2mA	70	–	700
Bandwidth	fT	VCE=12V, IC=10mA	–	100	MHz
Output Capacitance	Cob	VCB=10V, IE=0, f=1MHz	–	4	pF

This datasheet provides details on the 2SC945 transistor’s specifications, characteristics, and maximum ratings. It includes information on its maximum ratings such as collector-emitter voltage, collector current, power dissipation, as well as its electrical characteristics such as DC current gain, bandwidth, and output capacitance. It also mentions that the 2SC945 transistor is complementary to the 2SA733 transistor and is suitable for use in amplifier, oscillator, and switching applications.

2SC945 Transistor Pin Out Configuration

The pinout configuration of 2SC945 transistor is as follows:

• The leftmost pin (when viewing the flat side of the transistor with the pins facing downwards) is the emitter pin.
• The middle pin is the base pin.
• The rightmost pin is the collector pin.

Applications of 2SC945

2SC945 is a versatile NPN transistor that is in commonly use in a variety of electronic applications. Some of the applications of 2SC945 transistor are:

Amplifiers: 2SC945 is widely used in low-power audio and RF amplifiers due to its high DC current gain and good linearity.

Oscillators: It can also be used as an oscillator, especially in the RF frequency range.

Switches: 2SC945 can be used as a switch in digital circuits, such as logic gates and flip-flops.

LED driver circuits: It can be used in LED driver circuits due to its ability to drive a relatively high current.

Voltage regulator circuits: 2SC945 can be used in voltage regulator circuits as a pass transistor, especially in low-power applications.

Darlington pair: 2SC945 is also used in Darlington pair configuration to provide high current gain in high current applications.

Overall, the 2SC945 transistor is a widely in use component in various electronic circuits due to its high gain, good linearity, and versatility in various applications.

Equivalent to 2SC945

There are several equivalent transistors to 2SC945, which can be used as a replacement in electronic circuits. Some of the equivalents to 2SC945 are:

• BC547: BC547 is an NPN transistor with similar characteristics and can be used as a replacement for 2SC945 in most applications.
• 2N2222: 2N2222 is another NPN transistor that is widely used as a general-purpose transistor and is a suitable replacement for 2SC945 in many circuits.
• 2SA1015: 2SA1015 is a PNP transistor that is complementary to 2SC945 and can be used in place of 2SC945 in complementary amplifier circuits.
• 2N3904: 2N3904 is a widely used NPN transistor with similar characteristics to 2SC945 and can be used as a replacement in most applications.

It is important to note that while these transistors are similar in characteristics and can be used as a replacement for 2SC945 in many circuits, their pinouts may be different, and proper care should be taken while replacing a transistor to ensure that the pinouts are compatible with the circuit.

Difference between 2SC945 and C1815 Transistor

Both the C1815 and 2SC945 are bipolar junction transistors (BJTs) used for amplification and switching applications. There are a few distinctions between them, though:

• Maximum ratings: The C1815 has a maximum collector-emitter voltage (VCEO) of 50V and a maximum collector current (IC) of 150mA, while the 2SC945 has a maximum VCEO of 50V and a maximum IC of 150mA. This means that both transistors have similar maximum ratings.
• Gain: The gain of a transistor is the ratio of the output current to the input current. The C1815 has a typical DC current gain (hFE) of 70 to 700, while the 2SC945 has a typical hFE of 120 to 800. This means that the 2SC945 has a higher gain than the C1815.
• Frequency response: The frequency response of a transistor refers to its ability to amplify signals of different frequencies. The C1815 has a frequency response range of 40Hz to 100MHz, while the 2SC945 has a frequency response range of 150Hz to 300MHz. This means that the 2SC945 is better suited for high-frequency applications.
• Package type: The C1815 is available in a TO-92 package, while the 2SC945 is available in a TO-92 or TO-126 package. The TO-126 package has a larger heat-dissipating surface area and can handle higher power dissipation.

In summary, while both transistors are similar in terms of their maximum ratings, the 2SC945 has a higher gain and better frequency response, making it more suitable for high-frequency applications. Additionally, the 2SC945 is available in a TO-126 package, which can handle higher power dissipation.

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