ZHCS916I March 2009 – December 2018 TMP112
The TMP112 family supports the SMBus alert function. When the TMP112 family operates in interrupt mode (TM = 1), the ALERT pin can be connected as an SMBus alert signal. When a master senses that an alert condition is present on the alert line, the master sends an SMBus ALERT command (0001 1001) to the bus. If the ALERT pin is active, the device acknowledges the SMBus ALERT command and responds by returning the slave address on the SDA line. The eighth bit (LSB) of the slave address byte indicates if the alert condition is caused by the temperature exceeding T(HIGH) or falling below T(LOW). The LSB is high if the temperature is greater than T(HIGH), or low if the temperature is less than T(LOW). Refer to the Figure 13 section for details of this sequence.
If multiple devices on the bus respond to the SMBus ALERT command, arbitration during the slave address portion of the SMBus ALERT command determines which device clears the alert status of that device. The device with the lowest two-wire address wins the arbitration. If the TMP112 family wins the arbitration, the TMP112 family ALERT pin becomes inactive at the completion of the SMBus ALERT command. If the TMP112 family loses the arbitration, the TMP112 family ALERT pin remains active.