±1% at 4.096 V — the reference floor for a 12-bit ADC
The LM4040DIM3-4.1 is a precision shunt voltage reference from Texas Instruments, delivering a fixed 4.096 V output with ±1% initial tolerance. This output voltage is a common full-scale reference for 12-bit ADCs and DACs operating on a 5 V rail, where each LSB represents exactly 1 mV. The shunt topology means it behaves like a two-terminal Zener — the load and bias resistor set the cathode current, which must stay between 78 µA (minimum) and 15 mA (maximum) for regulation.
80 µVrms noise and 150 ppm/°C drift — budget for precision
Wideband noise is specified at 80 µVrms over 10 Hz to 10 kHz — about 20 LSBs on a 12-bit system at 4.096 V. That is acceptable for general-purpose data acquisition, but a lower-noise reference (e.g., 10 µVrms) would be needed for 16-bit or higher resolution.
NRND — design it out now
That means existing production can be sourced, but new BOMs should select a current-series part. For a direct ±1% replacement, the LM4040AIM3-4.1 is the closest active sibling.
SOT-23-3 — footprint fits standard analog layouts
This three-pin footprint is industry-standard for shunt references and small-signal transistors, so board layout reuse across alternate vendors is straightforward.