Precision shunt reference for 5V rails
The LM4050CEM3-5.0/NOPB is a precision shunt voltage reference from Texas Instruments that delivers a fixed 5V output with ±0.5% initial tolerance. This is the component engineer's go-to for a stable reference in a three-pin SOT-23-3 package — no external passives beyond a single cathode resistor are needed to set the operating point.
The shunt reference sinks up to 15 mA through the cathode, so the series resistor must be sized to keep the total current — reference plus any load — below this ceiling. Minimum cathode current is 90 µA; below that the reference drops out of regulation, so the resistor value has a lower bound even at no load. For a 5V reference feeding a 16-bit ADC with a 5V input range (76 µV per LSB), this noise contributes roughly 1.2 LSBs of rms uncertainty — acceptable for most industrial acquisition but worth a pre-filter if the signal chain targets better than 14 ENOB.