TL431 Regulator : Pin Configuration & Its Applications

• The TL431 Regulator is a shunt voltage regulator IC with adjustable precision. The output voltage can be programmed by changing the values of the connected resistors. As a result, it is known as a programmable shunt regulator. The operation of this IC is nearly identical to that of a Zener diode, with the exception that the voltage rating is programmable.
• It is also known as an adjustable Zener diode. It is primarily used in electrical circuits to provide positive or negative voltage reference. It is inexpensive and widely used as a reference voltage provider in isolated power supply circuits. The TL431 regulator chip is depicted in the diagram below.

• It is a 3-terminal shunt voltage regulator diode integrated circuit that comes in a To-92 package. The resistor divider connected to the IC’s reference terminal is changed to increase the output voltage rating from 2.5 to 36 Volts. The operating current is between 1 and 100 mA, with a typical impedance of 0.22 Ohms.
• It delivers consistent performance over a wide temperature range. It is used in a variety of applications when Zener diodes need to be replaced because its operation is nearly identical to that of a Zener diode except that the output voltage is programmable and adjustable. It is widely used as a reference voltage source in overvoltage and Under voltage monitoring circuits, window voltage monitoring circuits, and power supplies.

TL431 Regulator Pin Configuration

• The TL431 regulator is a 3-terminal shunt regulator with certain thermal stability over the automotive, military, and commercial temperature ranges. The figure below depicts the TL431 regulator pin configuration/pin diagram. The TL431 regulator diode’s schematic symbol is shown in the figure below.

• Pin1 (Reference): It is used to set the voltage rating of the Zener diode.
• Pin2 (Anode): It is the anode terminal of the equivalent Zener diode.
• Pin3 (Cathode): It is the cathode terminal of the equivalent Zener diode.

Applications of TL431 Regulator

• The applications of the TL431 regulator are listed below.
• It is used in SMPS (Switch Mode Power Supplies)
• It is used in circuits of isolated power supplies.
• Used in voltage comparators with integrated reference.
• Used in current regulation circuits.
• Used in precision reference voltage source circuits.
• Used in regulated power supply circuits, which are adjustable.
• Used in circuits of overvoltage protection.
• Used in voltage monitors.
• Used in constant current source circuits.
• Used in controllable shunt characteristics.
• Used when replacement of Zener diodes is required.
• Used in solar applications.
• Used in monitor and battery charger circuits.