Adjustable shunt reference — what the 2.495 V minimum and 36 V maximum mean for your rail
The TL431CZ-AP is an adjustable shunt voltage reference from STMicroelectronics, part of the industry-standard TL431 family. Its output is set with two external resistors from a minimum of 2.495 V up to 36 V, covering common 3.3 V, 5 V, 12 V, 24 V, and 30 V rails. The 100 mA cathode current rating defines the shunt path's maximum current — size the cathode resistor so that the total current (load plus reference quiescent) stays under 100 mA at the lowest input voltage. The ±2.21% tolerance is a general-purpose grade; for designs needing better than 1%, a tighter-tolerance sibling like the TL1431 would be the next step. The TO-92 through-hole package with formed leads suits hand-assembly, prototyping, and legacy board retrofits where SMD rework is impractical.
The base product number TL431 is a long-running industry standard with multiple qualified sources, so supply risk is low even if this specific package variant tightens.
Because the part is active and widely second-sourced across the TL431 family, lead times tend to be stable, but the exact position is verified per request. No single-source exposure here — qualify the alternate now if you want a second BOM leg.