The temperature limits are stored in the T_(LOW) and T_(HIGH) registers in the same format as the temperature result, and the 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 T_HIGH 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 T_LOW 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 T_(HIGH) for a consecutive number of fault conditions (as shown in Table 6-5). 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 T_(LOW), 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 T_(HIGH). 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 6-7. Table 6-13 through Table 6-16 describe the format for the T_HIGH and T_LOW registers. Note that the most significant byte is sent first, followed by the least significant byte. Power-up reset values for T_HIGH and T_LOW are: T_HIGH = 80°C and T_LOW = 75°C. The format of the data for T_HIGH and T_LOW is the same as for the Temperature Register.