DS7505 Datasheet, PDF (7/14 Pages) Maxim Integrated Products – Digital Thermometer and Thermostat

Digital Thermometer and Thermostat
IN THIS EXAMPLE, THE DS7505 IS CONFIGURED
TO HAVE A FAULT TOLERANCE OF 2.
TOS
TEMPERATURE
THYST
INACTIVE
O.S. OUTPUT—COMPARATOR MODE
ACTIVE
INACTIVE
O.S. OUTPUT—INTERRUPT MODE
ACTIVE
Figure 4. O.S. Output Operation Example
ASSUMES A READ
HAS OCCURED
CONVERSIONS
Interrupt Mode
In interrupt mode, the O.S. output first becomes active
when the measured temperature exceeds the TOS
value a consecutive number of times equal to the FT
value in the configuration register. Once activated, O.S.
can only be cleared by either putting the DS7505 into
shutdown mode or by reading from any register (tem-
perature, configuration, TOS, or THYST) on the device.
Once O.S. has been deactivated, it is only reactivated
when the measured temperature falls below the THYST
value a consecutive number of times equal to the FT
value. Again, O.S can only be cleared by putting the
device into shutdown mode or reading any register.
Thus, this interrupt/clear process is cyclical between
TOS and THYST events (i.e, TOS, clear, THYST, clear,
TOS, clear, THYST, clear, etc.). Thermostat interrupt
mode operation with FT = 2 is illustrated in Figure 4.
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