The TMP110 has alert feature and uses the TLow_limit register for low threshold comparison and THigh_Limit register for high threshold comparison. The alert limit is programmed in the TMP110 in a 12-bit or 13-bit two's complement format based on the Extended_Mode setting in the configuration register, with a resolution of 62.5 m°C. At the end of each temperature conversion, the temperature result is compared with the high limit and low limit registers, and the alert status flag and/or ALERT pin is updated.

The alert status flag in configuration register and/or the ALERT pin are updated based on the Alert_Mode and Polarity bit setting in the configuration register after every temperature conversion.

As shown in Figure 7-3, in comparator mode (Alert_Mode = 0b), the ALERT pin and status flag become active when the temperature equals or exceeds the value in THigh_Limit for Fault number of consecutive conversions. The ALERT pin and status flag remain active until the temperature falls below the TLow_Limit for the same number of consecutive conversions.

Figure 7-3 Comparator Mode

As shown in Figure 7-4, in alert mode (Alert_Mode = 1b), the ALERT pin becomes active only when the temperature equals or exceeds the THigh_Limit for Fault number of consecutive conversion. The ALERT pin remains active, until a read operation of any register occurs, or the device responds to the SMBus Alert Response. When the ALERT pin is cleared, the pin becomes active only when the temperature is less than the TLow_Limit for Fault number of consecutive conversion and remains active, until a read operation of any register occurs, or the device responds to the SMBus Alert Response. When the ALERT pin is cleared after a TLow_Limit crossing, the above cycle repeats. The ALERT pin and status can also be cleared by issuing the General Call Reset command.

Figure 7-4 Alert Mode