TL431
The TL431 integrated circuit (IC) is a three-terminal adjustable precise shunt voltage regulator. With the use of an external voltage divider, a TL431 can regulate voltages ranging from 2.495 to 36 V, at currents up 100 mA. The typical initial deviation of reference voltage from the nominal 2.495 V level is measured in millivolts, the maximum worst-case deviation is measured in tens of millivolts.