STCN75_08 Datasheet, PDF (12/35 Pages) STMicroelectronics – Digital temperature sensor and thermal watchdog

Operation
STCN75
2.3
Comparator mode
In comparator mode, each time a temperature-to-digital (T-to-D) conversion occurs, the new
digital temperature is compared to the value stored in the T_OS and T_HYS registers. If a fault
tolerance number of consecutive temperature measurements are greater than the value
stored in the T_OS register, the OS/INT output will be asserted.
For example, if the FT1 and FT0 Bits are equal to “10” (fault tolerance = 4), four consecutive
temperature measurements must exceed T_OS to activate the OS/INT output. Once the
OS/INT output is active, it will remain active until the first time the measured temperature
drops below the temperature stored in the T_HYS register, whereupon it will reset to its
inactive state.
Putting the device into shutdown mode does not clear OS/INT in comparator mode.
2.4
Interrupt mode
In Interrupt mode, the OS/INT output becomes active when the measured temperature
exceeds the T_OS value a consecutive number of times as determined by the Fault Tolerance
bits (FT1, FT0) value in the configuration register. Once activated, the OS/INT can only be
cleared by reading from any register (temperature, configuration, T_OS, or T_HYS) on the
device. Once the OS/INT has been deactivated, it will only be reactivated when the
measured temperature falls below the T_HYS value a consecutive number of times equal to
the FT value. This mode is better suited for interrupt driven microprocessor based systems.
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