3 V shunt reference — what the ±1% tolerance buys the design
The LM4040DEM3-3.0 is a fixed 3 V shunt voltage reference from the LM4040 family, housed in a SOT-23-3 package. The ±1% initial tolerance sets the reference accuracy floor — adequate for 8- to 10-bit ADC/DAC systems or comparator thresholds where a tight bandgap is not required. The shunt topology means it behaves like a Zener diode: a series resistor from the supply to the cathode sets the bias current, and the reference regulates the cathode voltage to 3 V as long as the cathode current stays between 75 µA and 15 mA.
Temperature range and noise — industrial-grade reference
The 150 ppm/°C temperature coefficient means the output can drift up to 45 mV across the full temperature range from the 3 V nominal — a 1.5 % shift that may require calibration in a 12-bit system.
The LM4040DEM3-3.0 is marked obsolete. Buyers sourcing this part should expect to procure it through independent distribution or surplus channels. No official successor is listed on the record, so a pin-compatible replacement must be validated against the BOM's voltage and tolerance requirements.