A digital IC TWO TERMINAL VOLTAGE REFERENCE is coupled to the voltage reference ic.The part has 3 pins.There is a part with 3 pins that have been settled.
LM4040BTB-122GT3 Features
TWO TERMINAL VOLTAGE REFERENCE Analog IC
LM4040BTB-122GT3 Applications
There are a lot of ON Semiconductor LM4040BTB-122GT3 Voltage Reference applications.