The DS1631, DS1631A, and DS1731 digital thermometers provide 9, 10, 11, or 12-bit temperature readings over a -55C to +125C range. The DS1631 and DS1631A thermometer accuracy is 0.5C from 0C to +70C with 3.0V VDD 5.5V, and the DS1731 accuracy is 1C from -10C to +85C with 3.0V VDD 5.5V. The thermostat on all three devices provides custom hysteresis with user-defined trip points (TH and TL). The TH and TL registers and thermometer configuration settings are stored in NV EEPROM so they can be programmed prior to installation. In addition, the DS1631A automatically begins taking temperature measurements at power-up, which allows it to function as a stand-alone thermostat. Communication with the DS1631/DS1631A/DS1731 is achieved through a 2-wire serial interface, and three address pins allow up to eight devices to be multidropped on the same 2-wire bus. Pin descriptions for the DS1631/DS1631A/DS1731 are provided in Table 2 and user-accessible registers are summarized in Table 3. A functional diagram is shown in Figure 1. 1 of 14