The TMP411-Q1 and TMP411D-Q1 devices have two pins dedicated to alarm functions, the THERM and ALERT/ THERM2 pins. Both pins are open-drain outputs that each require a pullup resistor to V+. These pins can be wire-ORed together with other alarm pins for system monitoring of multiple sensors. The THERM pin provides a thermal interrupt that cannot be software-disabled. The ALERT pin is intended for use as an earlier warning interrupt, and can be software disabled, or masked. The ALERT/ THERM2 pin can also be configured for use as a THERM2 pin, which is a second THERM pin (Configuration Register: AL/TH bit = 1). The default setting configures pin 6 to function as the ALERT pin (AL/TH = 0).

The THERM pin asserts low when either the measured local or remote temperature is outside of the temperature range programmed in the corresponding Local or Remote THERM Limit Register. The THERM temperature limit range can be programmed with a wider range than that of the limit registers, which allows the ALERT pin to provide an earlier warning than the THERM pin. The THERM alarm resets automatically when the measured temperature falls within the THERM temperature limit range minus the hysteresis value stored in the THERM Hysteresis Register. The permitted hysteresis values are shown in Table 8-8. The default hysteresis is 10°C. When the ALERT/ THERM2 pin is configured as a second thermal alarm (Configuration Register: bit 7 = 0, bit 5 = 1), the pin functions the same as the THERM pin, but uses the temperatures stored in the Local/Remote Temperature High/Low Limit Registers to set the comparison range.

When ALERT/ THERM2 (pin 6) is configured as ALERT pin (Configuration Register: bit 7 = 0, bit 5 = 0), the pin asserts low when either the measured local or remote temperature violates the range limit set by the corresponding Local/Remote Temperature High/Low Limit Registers. This alert function can be configured to assert only if the range is violated a specified number of consecutive times (1, 2, 3, or 4). The consecutive violation limit is set in the Consecutive Alert Register. False alerts that occur as a result of environmental noise can be prevented by requiring consecutive faults. The ALERT pin also asserts low if the remote temperature sensor is open-circuit. When the MASK function is enabled (Configuration Register: bit 7 = 1), the ALERT pin is disabled (that is, masked). The ALERT pin resets when the controller reads the device address, as long as the condition that caused the alert no longer persists, and the Status Register is reset.