SNOSD82C June 2018 – April 2021 TMP117
The TMP117 supports the SMBus alert function. When the ALERT pin is connected to an SMBus alert signal and a master senses that an alert condition is present, the master can send out 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). See Figure 7-11 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 TMP117 wins the arbitration, the TMP117 ALERT pin becomes inactive at the completion of the SMBus ALERT command. If the TMP117 loses the arbitration, the TMP117 ALERT pin remains active.