What is a constant current transistor, its structure, characteristics, and application techniques 1

A constant current transistor is a special type of transistor that can achieve a constant collector current output by controlling the base current. In electronic circuits, constant current transistors are widely used in fields such as power supply, current source, and current control.

1、 Structure of Constant Current Transistor

The structure of the constant current transistor LM393N is similar to that of a regular transistor, consisting of an emitter, base, and collector. However, the constant current transistor has some special designs in its structure, such as adding a stabilizing diode, which enables it to achieve a constant collector current output.

Among them, R1 is the current limiting resistor, R2 is the base resistor, RG is the current stabilizing diode, and C is the bypass capacitor. A steady current diode is the core component of a constant current transistor, whose main function is to maintain a constant current at a constant voltage.

2、 Characteristics of Constant Current Transistor

1. Constant current output: Under normal operating conditions, the collector current of a constant current transistor is not significantly affected by input voltage and output load, thus exhibiting a constant current output characteristic.

2. High precision: Constant current transistors have high-precision current output, typically achieving an accuracy of around 0.1%.

3. Good stability: Constant current transistor have good temperature stability and power supply stability, and can operate within a wide temperature range and power supply fluctuation range.

4. Low noise: Due to the stable current output of the constant current transistor, its noise level is relatively low.

5. Low output voltage: The output voltage of a constant current transistor is usually low, ranging from a few hundred mV to several V.