2.048 V shunt reference for precision ADC/DAC bias
The LM4040CECT-2.0 is a precision micropower shunt voltage reference from the LM4040 family, delivering a fixed 2.048 V output. This voltage is a natural ratiometric reference for 12-bit and 16-bit ADCs and DACs where the full-scale input is 2.048 V, simplifying the system voltage-divider math. The ±0.5% initial tolerance sets the uncalibrated accuracy floor for the measurement chain — a ±10.24 mV window at 25°C before temperature drift is factored in.
Temperature drift and noise floor
Temperature coefficient is 70 ppm/°C typical, which means the output shifts about 143 µV per 10°C change. Low-frequency noise is specified at 10 µVp-p over 0.1 Hz to 10 Hz, which is clean enough for a 12-bit system without external filtering.
Output drive and cathode current
The shunt architecture requires an external series resistor from the supply to the reference cathode. The device sinks 10 µA minimum cathode current to maintain regulation, and can source up to 15 mA to the load. This 15 mA ceiling is enough to bias several ADC reference inputs or a small resistor divider, but not enough to drive an external buffer stage — if the load exceeds 15 mA, the output drops out of regulation. The minimum cathode current of 10 µA means the series resistor must be sized so that the total current (load + 10 µA) flows at all times, even at the minimum supply voltage.
Package and footprint for tight layouts
Housed in a 5-pin SOT-353 (also marked as SC-70-5 or SOT-323-5).