The TL431 integrated circuit consists of a programmable shunt regulator with an internal operational amplifier exciting a bipolar transistor. In the configuration shown in the figure, the TL431 circuit is used as a reference for a block that provides an output voltage of 24 V under current up to 2.5 A. The gain of the transistor used is 1 000 and the current in its base of about 7.5 mA. Other transistors with different current capacity and equivalent gain can be used in the same configuration. The relationship between the output resistors determines the voltage. These components can have their values changed if the reader wishes to program the output voltage to another value.
