DS1775 Datasheet, PDF (5/13 Pages) Dallas Semiconductor – SOT23-5 Digital Thermometer and Thermostat

O.S. OUTPUT TRANSFER FUNCTION Figure 2
DS1775
Regardless of the mode chosen, the O.S. output is open–drain and the active state is set in the
configuration register. The power–up default is active low. Refer to the “OPERATION–Programming”
section for instructions in adjusting the thermostat setpoints, thermostat mode, and O.S. active state.
OPERATION–Programming
There are three areas of interest in programming the DS1775: the configuration register, the T_OS register,
and the T_HYST register. All programming is done via the 2–wire interface by setting the pointer to the
appropriate location. Table 3 illustrates the pointer settings for the four registers of the DS1775.
Pointer Register Structure Table 3
POINTER
ACTIVE REGISTER
00h
Temperature (default)
01h
Configuration
02h
T_HYST
03h
T_OS
The DS1775 will power up with the temperature register selected. If the host wishes to change the data
pointer it simply addresses the DS1775 in the write mode (R/ W =0), receives an acknowledge, and writes
the 8 bits that correspond to the new desired location. The last pointer location is always maintained so
that consecutive reads from the same register do not require the host to always provide a pointer address.
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