What this shunt reference delivers
The STMicroelectronics TL1431ACL5T is an adjustable shunt voltage reference in a SOT-23-5 package. It holds the output at 2.5 V minimum up to 36 V maximum, programmed by two external resistors. The ±0.25% tolerance and 90 ppm/°C temperature coefficient make it a fit for precision feedback loops.
Output current and cathode current — what they mean for the loop
Rated for 100 mA output and a minimum cathode current of 600 µA. The 100 mA ceiling sets the shunt resistor's power dissipation budget in a typical series-pass regulator or optocoupler drive circuit. The 600 µA minimum cathode current is the knee below which the reference loses regulation — the bias resistor from cathode to supply must pull at least that much to keep the part in its linear band. Design the bias resistor for worst-case supply and load so the cathode current never dips below 600 µA.
Temperature range and where it goes
Rated for -20°C to 70°C ambient. That is a commercial temperature grade.