SBOS397H August 2007 – December 2018 TMP102
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 becomes 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 5). 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 will also be 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, and 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, with the ALERT pin becoming active when the temperature equals or exceeds THIGH. The ALERT pin can also be 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 represented in Figure 13. Table 13 through Table 16 describe 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.