Temperature sensing can be one of the more challenging physical entities to measure if a variety of ranges and levels of accuracy are required by one electrical system. The circuit in Figure 1 uses a low power, single-supply analog-to-digital converter, ADS7816, configured with a thermocouple and CJC sub-circuit to achieve the desired range of responsiveness as well as high accuracy. The thermocouple is interfaced with a 12-bit A/D converter that allows for an adjustable input range. This range is adjusted with the voltage reference input. The range of the voltage reference input of the ADS7816 A/D converter is from the supply voltage (+5V typically) all the way down to 0.1V. The voltage reference range mimics a gain stage for the 12-bit converter. With this converter a suto-gain stage provides 17.6-bit virtual resolution against a 5V scale. When this circuit is properly calibrated for the desired temperature range, the effective resolution can be increased by 50x over a system with a standard 5V full-scale range.