View lm431b datasheet:

www.fairchildsemi.com LM431A/LM431B/LM431C Programmable Shunt Regulator Features Description � Programmable Output Voltage to 36 Volts The LM431A/LM431B/LM431C are three terminal output � Low Dynamic Output Impedance 0.20 Typical adjustable regulators with thermal stability over operating � Sink Current Capability of 1.0 to 100mA temperature range. The output voltage can be set any value � Equivalent Full-Range Temperature Coefficient of between V (approximately 2.5 volts) and 36 volts with REF 50ppm/�C Typical two external resistors. These devices have a typical dynamic � Temperature Compensated for Operation Over Full Rated output impedance of 0.2? Active output circuit provides a Operating Temperature Range sharp turn-on characteristic, making these devices excellent � Low O