2.048 V shunt reference with ±0.5% initial accuracy
The LM4040CEM3X-2.0 is a precision shunt voltage reference from Texas Instruments that delivers a fixed 2.048 V output with a ±0.5% initial tolerance. That 2.048 V level is a natural fit for 12-bit and 16-bit ADCs with a 4.096 V full-scale input — the math is a clean 1 LSB = 1 mV, no scaling resistor needed. As a shunt reference, it behaves like a Zener diode: you set the bias current through a series resistor from the supply, and the part sinks enough cathode current (68 µA typical, up to 15 mA) to regulate the output. The 68 µA minimum operating current means the reference can run from a high-impedance supply without loading it down.
Noise and drift for precision analog
Output noise is specified at 35 µVrms over the 10 Hz to 10 kHz bandwidth — low enough that a 16-bit ADC with a 4.096 V reference sees less than 0.3 LSB of reference-induced noise.
SOT-23-3 footprint and hand-solderability
The part comes in a SOT-23-3 package (also listed as TO-236-3 / SC-59). It is a three-pin device — cathode, anode, and no-connect — so the layout is straightforward. The SOT-23-3 is hand-solderable with a fine-tip iron; no hot-air or reflow is strictly required for prototyping.