The TMP110 device supports the SMBus alert response. When the TMP110 operates in Alert Mode, and the ALERT pin is available, the controller can sense that an alert condition is present. Irrespective of the availability of the ALERT pin, the alert status is set. As shown in Figure 7-12, if the controller sends an SMBus alert command (19h or 00011001b) on the bus, and the alert is set, the device acknowledges the SMBus alert command and responds by returning the device addess on the SDA line. The eigth bit (LSB) of the device address byte indicates if the alert condition was caused by the temperature exceeding THigh_Limit or falling below the TLow_Limit. The value of the eight bit follows the Polarity bit setting.

Figure 7-12 SMBus Alert Response

If multiple devices on the bus respond to the SMBus alert command, arbitration during the device address portion of the SMBus alert command determines which devices the ALERT pin is activated. The device with the lowest address wins the arbitration. On winning the arbitration, the TMP110 inactivates the ALERT pin and/or clears the status bit. To prevent the device with lowest I²C address in continuous conversion mode sees the alert line and halt others with higher I²C address to report the alert, the controller has to temporarily disable the Alert mode in device with smallest I²C address until all alerts in the system are cleared.