Precision shunt reference in a standard SOIC footprint
The Texas Instruments LM431BCMX is an adjustable shunt voltage reference with a 2.495 V minimum output and a ±1% tolerance band that holds the reference voltage tighter than the standard 2% grade — a meaningful difference when the ADC or comparator threshold budget is tight. Rated for 100 mA continuous cathode current and a 36 V maximum output, this part covers the common 3.3 V to 24 V rail-derived reference designs in industrial control and instrumentation. The 50 ppm/°C typical temperature coefficient means the output drifts less than 0.5 mV over a 10 °C change at the 2.5 V setpoint — stable enough for a 12-bit ADC reference without external trimming.
Package and operating range for board-level fit
Rated for -25 °C to 85 °C ambient operation, the temperature grade suits equipment in ventilated enclosures, telecom shelters, and factory-floor cabinets — not extended to the full -40 °C industrial band, so check the cold-end margin if the design sees outdoor startup below -25 °C. The shunt architecture requires a minimum 1 mA cathode current to maintain regulation; the external resistor from the supply rail to the cathode must be sized to deliver this at the lowest supply voltage and highest load current.