This part is a kind of semiconductor called TL431ACD.

Function of this product has Programmable Shunt Regulator.

Manufacturers : Fairchild Semiconductor

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Some of the text within the PDF file :

www.fairchildsemi.com TL431/TL431A Programmable Shunt Regulator Features • • • • Programmable Output Voltage to 36 Volts Low Dynamic Output Impedance 0.20 Typical Sink Current Capability of 1.0 to 100mA Equivalent Full-Range Temperature Coefficient of 50ppm/°C Typical • Temperature Compensated For Operation Over Full Rated Operating Temperature Range • Low Output Noise Voltage • Fast Turn-on Response Description The TL431/TL431Aare three-terminal adjustable regulator series with a guaranteed thermal stability over applicable temperature ranges. The output voltage may be set to any value between VREF (approximately 2.5 volts) and 36 volts with two external resistors These devices have a typical dynamic output impedance of 0.2W Active output circuitry provides a very sharp [ ... ]

TL431ACD PDF Datasheet Download