The TS431/431A/431B integrated circuits are three-terminal programmable shunt regulator diodes. These monolithic IC voltage references operate as a low temperature coefficient zener which is programmable from Vref to 36 volts with two external resistors.
Datasheets by Manufacturer
TS431 — STMicroelectronics — Adjustable shunt voltage reference
TS432 — STMicroelectronics — 1.24V ADJUSTABLE SHUNT VOLTAGE REFERENCE