Rainbow Electronics DS7505 - Manual (Page 7)

DS7505
Digital Thermometer and Thermostat
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IN THIS EXAMPLE, THE DS7505 IS CONFIGURED
TO HAVE A FAULT TOLERANCE OF 2.
T OS
T HYST
TEMPERATURE
O.S. OUTPUT—COMPARATOR MODE
O.S. OUTPUT—INTERRUPT MODE
INACTIVE
INACTIVE
ACTIVE
ACTIVE
CONVERSIONS
ASSUMES A READ
HAS OCCURED
Figure 4. O.S. Output Operation Example
Interrupt Mode
In interrupt mode, the O.S. output first becomes active
when the measured temperature exceeds the T
OS
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, T
OS , or T HYST ) on the device.
Once O.S. has been deactivated, it is only reactivated
when the measured temperature falls below the T HYST
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
T
OS and T HYST events (i.e, T OS , clear, T HYST , clear,
T OS , clear, T HYST , clear, etc.). Thermostat interrupt
mode operation with FT = 2 is illustrated in Figure 4.