What are the functions of the regulator diode in the application circuit?

What are the functions of the regulator diode in the application circuit?

The circuit symbol of a regulated diode (also known as a Zener diode) is: This diode is a semiconductor device with a very high resistance until the critical reverse breakdown voltage. At this critical breakdown point, the reverse resistance is reduced to a very small value, in which the current increases while the voltage remains constant in the low impedance region, and the Zener diode is binned according to the breakdown voltage, which is mainly used as a voltage regulator or voltage reference element. Zener diodes can be connected in series for use at higher voltages, and more stable voltages can be obtained by connecting them in series.

Applications of regulator diode:

1. Surge protection circuit: The regulator diode breaks down at the exact voltage, which makes it available as a limiting or protective component, because the regulator diode of various voltages can be obtained, so it is particularly suitable for this application. Just the power supply

When the voltage VS exceeds the regulated value D of the diode, it is turned on, so that the relay J picks up the load RL and separates it from the power supply.

2. Overvoltage protection circuit in the TV: EC is the main power supply voltage of the TV, when the EC voltage is too high, D is on, and the triode BG is turned on, and its collector potential will change from the original high level (5V) to low level, and the electricity is made through the control of the standby control line

The viewer enters the standby protection state.

3. Arc suppression circuit: If a suitable voltage regulator diode is connected in parallel on the inductor coil (it can also be connected to an ordinary diode in the same principle), when the coil is cut off in the conduction state, the high voltage generated by the release of electromagnetic energy is absorbed by the diode, so when the switch is disconnected, the arc of the switch is eliminated. This application circuit is used more in industry, such as some large-power electromagnetic control circuits.

4. Series regulator circuit: In this circuit, the base of the series regulator diode BG is clamped at 13V by the regulator diode D, then its emitter outputs a constant voltage of 12V. This circuit has applications in many situations.