Adjustable shunt reference in a three-pin SOT-23-3
The SOT-23-3 package fits tight board layouts where a TO-92 or SOIC-8 would consume too much area.
Output ceiling and cathode current — sizing the pass element
The maximum output voltage is 36 V, so this part works in 24 V or 12 V rails but not in a 48 V system. The cathode can sink up to 100 mA continuous, which sets the drive limit for an external transistor or optocoupler LED.
±2.2 % tolerance — where it fits the BOM
The ±2.2 % tolerance is wider than the 0.5 % or 1 % TL431 grades. It is a cost-optimised bin for designs where the reference accuracy does not dominate the system error budget — for example, a non-isolated bias supply, a simple overvoltage crowbar, or a secondary-side feedback loop in a consumer power supply. If the design needs tighter regulation, step up to the TL431A (1 %) or TL431B (0.5 %) variants.
It suits outdoor telecom enclosures, factory-floor sensor interfaces, and under-hood automotive auxiliary circuits that do not require AEC-Q100 qualification. The SOT-23-3 body has a low thermal mass, so keep the cathode current below 100 mA at the high end of the temperature range to stay inside the power-dissipation limit.