Triode, as a very common semiconductor device for controlling current, can amplify a small signal into a signal with large amplitude, which is used as a contactless switch in many circuits.

Triode is the core component of electronic circuit. It is made of two close PN junctions on a semiconductor substrate. The two PN junctions divide the whole semiconductor into three parts: collector region, base region and emitter region. As a common triode, the switching triode has the same shape as the common triode, and it works in the cutoff region and saturation region, which is equivalent to the cut-off and conduction of the circuit.

The switching transistor can control the on-off of large current with small current. The switching transistor works in the cut-off area and saturation area, which is equivalent to the cut-off and on-off of the circuit. It has the function of completing the cut-off and on-off, and is often used in various switching circuits, such as commonly used switching power supply circuits, high-frequency oscillation circuits, analog-to-digital conversion circuits, pulse circuits, driving circuits and output circuits. In this issue, Heketai will familiarize you with several common switching triode circuits and explain their working principles and applications.

Schematic diagram of classic switching triode circuit

As shown in the figure, when A is at high level, transistor 1 is turned on, so the output point B is at low level, which is the same as the emitter level. Because B is at low level, transistor 2 is turned off and output C is at high level.

When a is low, transistor 1 is turned off, so the output point B is high; Because B is at high level, transistor 2 is turned on and output C is at low level.

Switching triodes can be divided into low power switching tubes, medium power switching tubes and high power switching tubes due to different powers. The switching transistor has the characteristics of long life, safety and reliability, no mechanical wear, fast switching speed and small size. The low-power switching tube can be used in power supply circuit, driving circuit, switching circuit and so on. High-power tubes can be used for switching power supply of color TV sets and communication equipment, as well as low-frequency power amplification circuits and current adjustment. High back pressure and high power switch tube can be used for line output tube of color TV set. The switching triode produced by Heketai has the characteristics of safety, reliability, long service life, safety and reliability, no wear and fast switching speed, and is widely used in the above circuits. In addition, Heketai also has many models of diode, common triode, MOS transistor, bridge reactor, power management IC and other products, with stable and reliable product quality, good company service and complete package types. If you are interested in Heketai, you can contact Heketai customer service for consultation and quotation. Thank you!