What is a Darlington transistor? The basic structure, advantages and disadvantages, working principle, applications, installation, and market prospects of Darlington transistors 2

2. Disadvantages:

a. Higher saturation voltage drop: Due to the cascading effect, the saturation voltage drop of Darlington transistors is relatively high, generally between 1.2V and 1.4V.

b. Longer switching time: Due to the cascading effect, the switching time of Darlington transistors is longer, which may affect the performance of high-frequency applications.

3、 Working principle:

A Darlington transistors is composed of two cascaded transistors, typically consisting of two NPN or two PNP transistors. Among them, the first transistor is called the input transistor T1, and the second transistor is called the output transistor T2. The emitter of the input transistor is connected to the base of the output transistor, while the emitter of the output transistor serves as the output terminal of the entire circuit. The base of the input transistor serves as the input terminal of the circuit, and the collector of the output transistor serves as the input terminal of the circuit. Two transistors are connected through a resistor to provide feedback.

The working principle of Darlington transistors is based on the positive feedback effect. When the input voltage is applied to the base of the input transistor, the input transistor begins to conduct. Due to the base of the output transistor being connected to the emitter of the input transistor, the output transistor also begins to conduct. In this way, a larger current will flow through the emitter of the output transistor, thereby increasing the output current of the entire circuit. The increase in output current, in turn, leads to an increase in input current, forming positive feedback and enabling the Darlington transistors to have a high amplification factor.