4.096V fixed shunt — what it buys the ADC rail
The LM4040C41IDBZR is a precision shunt voltage reference from Texas Instruments, fixed at 4.096V with ±0.5% initial tolerance. That 4.096V output is a natural fit for 12-bit and 16-bit ADC reference inputs — the 1 mV per LSB mapping at 12 bits simplifies the math and keeps the full-scale range just under a typical 5V supply rail. As a shunt reference, it behaves like a Zener diode: it requires a series resistor from the supply and draws cathode current down to 88 µA. The 15 mA maximum output current limits the load it can drive directly — plan a buffer amplifier if the reference input of the ADC sinks more than a few hundred microamps.
Noise and drift — the precision metrics
Output noise is specified at 80 µVrms over the 10 Hz to 10 kHz band, which is low enough to not dominate the noise floor of a 12-bit ADC with a 4.096V reference (the LSB is 1 mV).
Package and procurement posture
The part comes in a standard SOT-23-3 package (also listed as TO-236-3 / SC-59), surface-mount only.