ADR420/ADR421/ADR423/ADR425 are ultraprecision low noise, 2.048 V/2.500 V/ 3.00 V/5.00 V XFET® voltage references from Analog Devices, Inc., with features such as low noise (0.1 Hz to 10 Hz), low temperature coefficient (3 ppm/�C), long-term stability (50 ppm/1000 Hours), load regulation (70 ppm/mA), line regulation (35 ppm/V), low hysteresis (40 ppm Typical).