Fixed 1.235 V shunt reference in 8-SOIC
The LT1004CD-1-2 is a two-terminal shunt voltage reference from Texas Instruments that delivers a fixed 1.235 V output with ±0.32% initial tolerance. The shunt topology means it operates like a precision Zener — no separate supply pin, just a cathode and anode — so it biases directly from the rail through a single resistor. Rated for 20 mA maximum cathode current and a minimum of 10 µA, this part can sink enough current to bias multiple ADC reference inputs or a small DAC array while keeping the quiescent floor low enough for battery-powered instrumentation. It ships in tube format, so plan for tube-fed or manual placement rather than tape-and-reel.
The temperature coefficient is 20 ppm/°C typical. For a 12-bit ADC with a 2.5 V reference, this drift contributes less than 1 LSB of error, so the LT1004CD-1-2 is clean for 12-bit systems and marginal for 14-bit without calibration. Output noise is specified at 60 µVrms integrated from 10 Hz to 10 kHz. That is low enough that the reference noise floor will not dominate the signal chain in a 12-bit, 1 kHz bandwidth measurement — the noise contribution is about 0.005% of the output voltage.
This makes it a drop-in replacement for any 1.235 V shunt reference in the same 8-SOIC footprint, as long as the resistor value is recalculated for the desired bias current.