The TL431 series Programmable Precision Reference feature low output noise voltage. The TL431A, B integrated circuit is programmable shunt regulator diode. This monolithic IC voltage reference operates as a low temperature coefficient zener which is programmable from Vref to 36V with two external resistors. This device exhibits a wide operating current range of 1 to 100mA with a typical dynamic impedance of 0.22Ω. The characteristics of this reference make them excellent replacements for zener diodes in many applications such as digital voltmeters, power supplies and op amp circuitry. The 2.5V reference makes it convenient to obtain a stable reference from 5V logic supplies and since the TL431A, B operates as a shunt regulator, it can be used as either a positive or negative voltage reference.