Voltage reference TLVH431
The internal ref voltage for a TLVH431 is 1.24 volts but this can vary a bit between about 1.2 volts and 1.28 volts so be aware of this. That reference voltage will appear at the reference input when you have feedback in place. If you use resistors forming a potential divider to the REF input then the voltage on the anode is: -



Picture taken from the data sheet.