STCN75_08 Datasheet, PDF (18/35 Pages) STMicroelectronics – Digital temperature sensor and thermal watchdog

Functional description
STCN75
3.1.5
Hysteresis temperature register (T_HYS)
T_HYS register is a two-byte (16-bit) READ/WRITE register that stores the user-
programmable lower trip-point temperature for the thermal alarm in two’s complement
format (see Table 8). This register defaults to 75°C at power-up (i.e., 0100 1011 0000 0000).
The format of this register is the same as that of the temperature register. The MSB position
contains the sign bit for the digital temperature and bit14 contains the temperature MSB.
Table 8.
Bytes
T_OS and T_HYS register format⁽¹⁾
HS byte
LS byte
MSB
TMSB
TLSB
LSB
Bits
15
14 13 12 11 10 9 8
7 654321 0
STCN75 S
TMSB
TD TD TD TD TD TD
9-bit
TLSB
0
0
0
0
0
0
0
Keys: S = two’s complement sign bit
TMSB = temperature MSB
TLSB = temperature LSB
TD = temperature Data
1. These are comparable formats to the DS75 and LM75.
3.2
Note:
Power-up default conditions
The STCN75 always powers up in the following default states:
● Thermostat mode = comparator mode
● Polarity = active-low
● Fault tolerance = 1 fault (i.e., relevant bits set to '0' in the configuration register)
● T_OS = 80°C
● T_HYS = 75°C
● Register pointer = 00 (temperature register)
After power-up these conditions can be reprogrammed via the serial interface.
18/35