TL431A Voltage Regulator IC: Common Uses and Pinout
By Kunkune | Published: 2026-10-27
Category: Tips & Care
Learn the TL431A pinout, common applications, and how to use this adjustable shunt voltage reference in your circuits.
Quick answer
The TL431A is a three-terminal adjustable shunt voltage reference that acts like a precision zener diode. Its pinout is straightforward: cathode, anode, and reference (adjust) pin.
Why choose the TL431A over a standard zener diode?
A standard zener diode has a fixed breakdown voltage and its accuracy depends on current and temperature. The TL431A gives you an adjustable output from 2.5V up to 36V with much better temperature stability and a typical initial tolerance of 1%. You set the voltage with just two external resistors.
Limitations to keep in mind
The TL431A is a shunt regulator, meaning it sinks current rather than sourcing it. It always needs a current-limiting resistor from the supply to the cathode. It cannot deliver output current like a series linear regulator (e.g., 7805). If your load draws more than 100 mA, look for a different part.
TL431A FAQ
- What is the TL431A pinout (TO-92 package)?
- Looking at the flat face with pins down: left pin is reference (adjust), middle pin is cathode, right pin is anode.
- How do I set the output voltage?
- Use two resistors as a voltage divider from cathode to reference and reference to anode. The formula is V_out = 2.5V × (1 + R1/R2). Choose R2 around 1kΩ to 10kΩ for stable operation. Always include a current-limiting resistor between the supply and the cathode to keep cathode current between 1 mA and 100 mA.
- What are the most common TL431 circuits?
- Over-voltage crowbar protection, precision shunt regulator for analog circuits, constant-current LED driver, and as a reference for switch-mode power supply feedback loops.
Product facts
- 10pcs TL431A TO-92 431 New Voltage Regulator IC: Voltage Regulator IC The 10pcs TL431A TO-92 pack gives you multiple units for prototyping or repairing several circuits at a low per-unit cost.
10pcs TL431A TO-92 431 New Voltage Regulator IC
