Q4X8E4

Thyristors - TRIACs

Q4X8E4 is a type of thyristor, more specifically a TRIAC. TRIACs are Thyristors which contain two thyristor cells, and is used for bidirectional load switching and phase control. TRIACs can be used in applications and systems where fast, repeatable and reliable switching is required. Some of the common applications for TRIACs are in heating and lighting control, motor speed control, digital signal control, AC dimmers, and door interlock switches.

TRIACs have four key terminals, the four terminals being the main terminals, the control terminal and the two gate terminals. The main terminals are the terminals between which the current flows when the TRIAC is turned on. The left main terminal is known as Anode 1 and the right main terminal is known as Cathode 2. The control terminal is connected to a source of trigger voltage while the gate terminals are used to control the operation of the TRIAC.

The working principle of a TRIAC is relatively simple; when a voltage is applied between the two gate terminals, current flows from the main terminal of one thyristor cell to the main terminal of the other thyristor cell. This causes a current path to be established between the two main terminals and the load current to be allowed to flow. This process is known as conduction phase, and is used to switch current from either direction. Since the two thyristor cells allow current from either direction, the TRIAC is classified as a bidirectional load switching device.

To turn the TRIAC off, current flow is interrupted by changing the voltage applied between the two gate terminals. This is known as the off phase, and is used when no current should be allowed to flow. The three stages of operation (on, off, and conducting) are carried out using the four terminals, allowing the TRIAC to be used to control the amount of current flowing through the device, by adjusting the voltage between the gate terminals.

The use of TRIACs allows devices and systems to be controlled in a safe and efficient manner, with a wide range of applications in both consumer and industrial electronics. TRIACs are also available in different sizes and power handling capabilities, making them suitable for a wide range of applications. With the use of modern manufacturing processes, the cost of TRIACs has also decreased, making them an economical solution for a number of applications.