The ±2.2% tolerance on the TL431QDBVR means the reference voltage at the cathode can vary by up to 55 mV around the nominal 2.495 V minimum. If your design needs better than 1% initial accuracy, you step up to the TL431A or TL431B grade variants — but for general-purpose adjustable supplies, optocoupler feedback loops, and comparator thresholds, ±2.2% is the standard production-grade spec that keeps BOM cost down.
Adjustable from 2.495 V to 36 V — one part covers multiple rails
With a minimum cathode voltage of 2.495 V and a maximum of 36 V, this single shunt reference can serve as a precision 2.5 V local reference for an ADC, a 5 V shunt regulator for an isolated flyback feedback loop, or a 24 V clamp in an industrial sensor interface. The 100 mA output current rating gives enough headroom to drive the optocoupler LED plus bias resistors in most isolated power supplies without needing a buffer transistor.
The SOT-23-5 package keeps the footprint small, but the thermal performance is adequate for the 100 mA maximum cathode current — just ensure the PCB copper area around the device can sink the dissipation at high ambient temperatures.
Package and mounting — SOT-23-5, surface-mount only
Supplied in the SOT-23-5 package, this is a surface-mount device intended for reflow assembly. No through-hole variant exists for this order code.