2.5 V shunt reference with ±0.2% initial accuracy
The Texas Instruments LM4040B25IDBZRG4 is a precision shunt voltage reference that delivers a fixed 2.5 V output with a ±0.2% initial tolerance.
100 ppm/°C drift over the industrial temperature band
That means the 2.5 V output can shift by roughly 3 mV worst-case from 25 °C to either extreme — a figure that matters if the reference is feeding a 12-bit ADC where 1 LSB at 2.5 V is about 610 µV. The 35 µVrms noise (10 Hz to 10 kHz) is low enough not to degrade the ADC's SNR in most precision signal-chain designs.
Shunt architecture — cathode current and load limits
As a shunt reference, the LM4040B25IDBZRG4 sinks current through the cathode to regulate the output. The minimum cathode current is 80 µA; the maximum continuous output current is 15 mA. The design rule: the series resistor from the supply must deliver enough current to cover both the load and the 80 µA minimum, but stay below the 15 mA ceiling when the load is at its minimum. That 80 µA quiescent floor makes this part suitable for battery-powered circuits where every microamp counts.
SOT-23-3 footprint and supply posture
The part comes in a standard SOT-23-3 surface-mount package (TO-236-3 / SC-59 equivalent).