SOT-23-3 shunt reference — the BOM workhorse
It provides a 2.495 V reference threshold and can be programmed via two external resistors to any output voltage between that minimum and 36 V.
100 mA cathode current and the feedback loop budget
The 100 mA output current rating defines the maximum sink current through the cathode. In an SMPS feedback application, this sets the bias current available for the optocoupler LED and any pull-up resistor — typically 1 mA to 10 mA is sufficient, leaving headroom for transient loads. Designs must ensure the cathode current never drops below this threshold at the minimum input voltage, or the reference output will drift out of regulation.
±2.2% tolerance — precision without the premium
The ±2.2% tolerance on the reference voltage sits between the standard ±2.5% and the tighter ±1% or ±0.5% grades. For an 8-bit ADC reference or a 12 V rail feedback divider, this is adequate precision at a lower cost than a 0.5% part. If the design needs better than 2% initial accuracy, step up to the TL431A (1%) or TL431B (0.5%) variants.
This makes it suitable for outdoor telecom cabinets, motor drive enclosures, under-hood automotive electronics, and any environment where the PCB sees wide thermal cycling.