Shunt reference with adjustable output
The Texas Instruments LM431AIM/NOPB is a three-terminal adjustable shunt voltage reference in an 8-SOIC surface-mount package. It sets a nominal 2.495 V reference between the cathode and anode, and with an external resistor divider the output can be programmed anywhere from that minimum up to 37 V.
Tolerance and temperature drift
The ±2.2% initial tolerance on the reference voltage is the band the output lands in at 25 °C with no external divider error. For a 5 V rail derived from the 2.495 V reference, that translates to a ±110 mV spread before resistor tolerance is added — adequate for general-purpose power-supply feedback and threshold detection where a few percent error is acceptable. Over the full 125 °C span the reference shifts by roughly 6.25 mV typical — the dominant error term in most designs is the initial tolerance, not the drift, unless the circuit is trimmed at room temperature.
Supplied in a tube, the 8-SOIC package (0.154" body width, 3.90 mm) uses the standard JEDEC footprint shared by countless op-amps and comparators — the same land pattern serves the TL431 family and many other 8-pin SOIC shunt references. The surface-mount body suits reflow assembly on FR-4 with no special thermal management for the 100 mA output, though the power dissipation at high cathode voltage and current should be checked against the package's thermal impedance.
No minimum order threshold applies; the part is quoted per RFQ.