Voltage Regulator with TL431

The TL431 is a reference voltage source that is commonly used in the control circuit of isolated power supplies. Typically used to provide a precision reference voltage, the TL431 can also be configured as an analog controller by exploiting its on-board error amplifier. In this example, the design of a TL431-based type 2 voltage controller for a flyback converter is presented. The voltage control circuit regulates the output voltage of the 5 V winding and includes an optocoupler to maintain isolation between the input and output stages. The example circuit is shown below.


PLECS Blockset

  • PLECS Blockset 3.4 or newer
  • MATLAB 7.5 (R2007b) newer

PLECS Standalone

  • PLECS Standalone 3.4 or newer


The documentation can be downloaded here. You can download the example models for PLECS Blockset here and for PLECS Standalone here.