This is a circuit of board system monitoring for temperature and voltage condition. It uses the NE1617A. The NE1617A is a 2 channel temperature sensor. It can measure remote and internal sensor. It also supports up to nine devices per bus. The temperature data update is selectable from 125 ms to 16 seconds, if it is used in normal operation. An internal, the temperature reading can be forced by one-shot command. Here is the circuit :
The advantages of the NE1617A are progamable, has high accuracy, small, 16-pin QSOP packages and has an operating temperature of 0 to 120 °C. It can be used for applications where thermal monitoring of electrical components and hardware is critical.
The more advanced version of the NE1617A is the NE1619. Besides measures the remote and internal temperature, the NE1619 can be used to monitor nine different voltage. It has programmable voltage and temperature limits for controlling internal alarms and supports two devices per bus. It also has an on-chip A/D converter which supports data collection and other functions. The consistent conversion rate that is used by the NE1619 is approximately 500 ms. [Source: NXP Application Note]