SBOS702D October 2014 – December 2018 TMP102-Q1
The temperature limits are stored in the T(LOW) and T(HIGH) registers in the same format as the temperature result, and their values are compared to the temperature result on every conversion. The outcome of the comparison drives the behavior of the ALERT pin, which operates as a comparator output or an interrupt, and is set by the TM bit in the configuration register.
In Comparator mode (TM = 0), the ALERT pin is active when the temperature equals or exceeds the value in THIGH and generates a consecutive number of faults according to fault bits F1 and F0. The ALERT pin remains active until the temperature falls below the indicated TLOW value for the same number of faults.
In Interrupt mode (TM = 1), the ALERT pin becomes active when the temperature equals or exceeds the value in THIGH for a consecutive number of fault conditions as shown in Table 11. The ALERT pin remains active until a read operation of any register occurs, or the device successfully responds to the SMBus alert response address. The ALERT pin is cleared if the device is placed in shutdown mode. When the ALERT pin is cleared, it becomes active again only when temperature falls below TLOW. The pin remains active until cleared by a read operation of any register or a successful response to the SMBus alert response address. When the ALERT pin is cleared, the above cycle repeats, and the ALERT pin goes active when the temperature equals or exceeds THIGH. The ALERT pin is also cleared by resetting the device with the general call reset command. This action also clears the state of the internal registers in the device, returning the device to comparator mode (TM = 0).
Both operational modes are shown in Figure 14. Table 12 and Table 13 list the format for the THIGH and TLOW registers. Note that the most significant byte is sent first, followed by the least significant byte. Power-up reset values for THIGH and TLOW are: THIGH = 80°C and TLOW = 75°C. The format of the data for THIGH and TLOW is the same as for the temperature register.