Skip to datasheet
Adjustable shunt regulator

TL431 Working Principle

Learn how TL431 works with an illustrated explanation and practical readings.

Package view

TL431 at a glance

Follow the labeled connections and functional stages

TL431 working principle: illustrated functional stages, basic circuit and connections
Select the diagram to read it at full resolution.

How it works

3 stages · Explore one step at a time

Step 1 / 3

Limit the feed current

A 680 Ω resistor feeds the output from 12 V. It must cover load, divider and cathode currents.

Step 2 / 3

Sense the divided output

Two 10 kΩ resistors place about 2.495 V at REF when the output is near 5 V.

Step 3 / 3

Sink the remainder

The internal amplifier adjusts current from K to A. The output falls out of regulation if the load leaves too little cathode current.

Component view