Datasheet

Operation STLM75
10/40 Doc ID 13296 Rev 12
2 Operation
After each temperature measurement and analog-to-digital conversion, the STLM75 stores
the temperature as a 16-bit two’s complement number (see Table 5: Register pointers
selection summary on page 17) in the 2-byte temperature register (see Table 7 on page 18).
The most significant bit (S) indicates if the temperature is positive or negative:
● for positive numbers S = 0, and
● for negative numbers S = 1.
The most recently converted digital measurement can be read from the temperature register
at any time. Since temperature conversions are performed in the background, reading the
temperature register does not affect the operation in progress.
The temperature data is provided by the 9 MSBs (bits 15 through 7). Bits 6 through 0 are
unused. Table 3 on page 15 gives examples of the digital output data and corresponding
temperatures. The data is compared to the values in the T
OS
and T
HYS
registers, and then
the OS
is updated based on the result of the comparison and the operating mode.
The alarm fault tolerance is controlled by the FT1 and FT0 bits in the configuration register.
They are used to set up a fault queue. This prevents false tripping of the OS
/INT pin when
the STLM75 is used in a noisy environment (see Table 3 on page 15).
The active state of the OS
output can be changed via the polarity bit (POL) in the
configuration register. The power-up default is active-low.
If the user does not wish to use the thermostat capabilities of the STLM75, the OS
output
should be left floating.
Note: If the thermostat is not used, the T
OS
and T
HYS
registers can be used for general storage of
system data.