2.5 V shunt reference in a through-hole package — bench-friendly and still in active production
The Texas Instruments LM4040C25ILPR is a precision shunt voltage reference that holds a fixed 2.5 V output with a tolerance of ±0.5%. It comes in a TO-92-3 through-hole package — the same three-lead form factor that makes it a drop-in replacement on countless analog and mixed-signal boards. The reference is rated for 15 mA output current and draws a cathode current of 80 µA, which sets the bias resistor for the series leg. Noise from 10 Hz to 10 kHz is specified at 35 µVrms, and the temperature coefficient is 100 ppm/°C.
Industrial temperature range and active lifecycle — no LTB surprises
What the tolerance and output current mean for your bias network
The ±0.5% initial tolerance is tight enough for most 8- to 10-bit ADC references and comparator thresholds without external trimming. The 15 mA output ceiling and 80 µA cathode current together determine the series resistor value: pick R such that (Vcc - 2.5 V) / R stays between 80 µA and 15 mA over the full load and supply range. The 100 ppm/°C drift adds about 250 µV over a 60°C swing — negligible for a 2.5 V rail unless the ADC is 12-bit or better.