2.048V shunt reference — the precision anchor
The LM4040EEM3-2.0 is a fixed 2.048V shunt voltage reference from Texas Instruments, housed in a SOT-23-3 package. It delivers a stable 2.048V output with ±2% initial tolerance and a 150ppm/°C temperature coefficient, making it suitable for precision ADC references, comparator thresholds, and portable instrumentation where a low-drift, low-power bias rail is needed.
The 2.048V fixed output is the nominal reference voltage; the ±2% tolerance means the actual output at 25°C can range from 2.007V to 2.089V. For a 12-bit ADC with a 2.048V reference, that translates to a gain error of roughly ±8 LSBs before any temperature drift is factored in. As a shunt reference, the LM4040EEM3-2.0 sinks current through a series resistor from the supply rail. The 73 µA minimum cathode current sets the floor for the bias resistor calculation; the 15 mA maximum output current defines the load it can drive while staying within regulation. Output noise is specified at 35 µVrms over a 10 Hz to 10 kHz bandwidth — clean enough for most 10- to 12-bit ADC reference inputs without additional filtering.
Obsolete — sourcing reality and the replacement path
Sourcing for the LM4040EEM3-2.0 runs through independent distribution and surplus channels.