TL431 is a three-terminal adjustable shunt regulator. Common package forms include TO-92 and SOT-23, etc. Its three pins are: Cathode, Anode, and Reference (Ref).
It contains an internal 2.5V reference voltage source. When the voltage at the reference terminal exceeds 2.5V, the TL431 conducts. The output voltage can be set by using external resistors. The calculation formula for the output voltage is:, where is 2.5V (typical value), and and are external resistors.
In practical applications, the following points need to be noted:
It is necessary to ensure that the current through the cathode is greater than 1mA to ensure the normal operation of the TL431; but the current should not be too large to avoid burning the chip.
Resistor values should be reasonably selected according to specific circuit requirements, input and output voltages, and other parameters, and the power handling capacity of the resistors should be considered.
The pin sequence of TL431 produced by different manufacturers may vary. When using it, it is necessary to check the relevant data sheet or product specification to determine the correct pin arrangement.
It is necessary to ensure that the current through the cathode is greater than 1mA to ensure the normal operation of the TL431; but the current should not be too large to avoid burning the chip.
Resistor values should be reasonably selected according to specific circuit requirements, input and output voltages, and other parameters, and the power handling capacity of the resistors should be considered.
The pin sequence of TL431 produced by different manufacturers may vary. When using it, it is necessary to check the relevant data sheet or product specification to determine the correct pin arrangement.