The L431 is a three-terminal adjustable shunt regulator utilizing an accurate 2.5V band-gap reference. The output voltage can be set to any value between 2.5V (VREF) to 29V with two external resistors as shown in the typical application circuit. The device exhibit a wide operating current range of 0.4 to 100 mA with a typical dynamic impedance of 0.25. The characteristics of these reference make it excellent replacements for zener diodes in many applications such as digital voltmeters, power supplies, and op amp circuitry. The 2.5V volt reference makes it convenient to obtain a stable reference from 5.0V logic supplies. The L431 shunt regulator is available in three voltage tolerances (0.5%, 1.0% and 2%) and three package options (TO-92, SOT-23-3, SOT-23-5 and SOIC-8).