Precision shunt reference for feedback and regulation
The TL431AQPK is an adjustable precision shunt voltage reference from the TL431 family, offering a ±1% tolerance on the 2.495 V internal reference. It is the go-to part for closing the feedback loop in isolated power supplies, setting the output voltage in linear regulators, and providing a stable threshold in comparator-based monitoring circuits. The 100 mA cathode current capability lets it drive an optocoupler LED directly without an extra buffer transistor.
Rated for harsh environments
The SOT-89-3 package has a larger footprint and lower thermal resistance than the SOT-23, so it handles the thermal load when the cathode current is pushed toward the 100 mA maximum.