stcn75 STMicroelectronics, stcn75 Datasheet - Page 17

• Manufacturer Part Number: stcn75
• Description: Digital Temperature Sensor And Thermal Watchdog
• Manufacturer: STMicroelectronics

3.1.3
3.1.4
Temperature register
The Temperature register is a two-byte (16-bit) “Read only” register (see
temperatures from the T-to-D converter are stored in the Temperature register in two’s
complement format, and the contents of this register are updated each time the T-to-D
conversion is finished.
The user can read data from the Temperature register at any time. When a T-to-D
conversion is completed, the new data is loaded into a comparator buffer to evaluate fault
conditions, and will update the Temperature register if a read cycle is not ongoing. The
STCN75 is continuously evaluating fault conditions regardless of READ or WRITE activity
on the bus. If a READ is ongoing, the previous temperature will be read. The readable
temperature will be updated upon the completion of the next T-to-D conversion that is not
masked by a read cycle.
All unused bits following the digital temperature will be zero. The MSB position of the
Temperature register always contains the sign bit for the digital temperature, and Bit 14
contains the temperature MSB. All bits in the Temperature register default to zero at power-
up.
Table 7.
1. These are comparable formats to the LM75.
Over-limit temperature register (T
T
upper trip-point temperature for the thermal alarm in two’s complement format (see
on page
The format of the T
position contains the sign bit for the digital temperature and Bit14 contains the temperature
MSB.
For 9-bit conversions, the trip-point temperature is defined by the 9 MSBs of the T
register, and all remaining bits are “Don’t cares” (x).
STCN75
OS
Bytes
Bits
Keys: S = Two’s complement sign bit
register is a two-byte (16-bit) READ/WRITE register that stores the user-programmable
18). This register defaults to 80°C at power-up (i.e., 0101 0000 0000 0000).
TMSB = temperature MSB
TLSB = temperature LSB
TDx = temperature data bits
MSB
TD8
(S)
15
Temperature register format
(TMSB)
TD7
OS
14
register is identical to that of the Temperature register. The MSB
TD
13
6
HS byte
TD
12
5
TMSB
TD
11
4
TD
10
3
(1)
OS
TD
9
2
)
TD
8
1
(TLSB)
TD0
7
6
x
5
x
TLSB
LS byte
4
x
Table
3
x
7). Digital
2
x
OS
1
x
Table 8
17/35
LSB
0
x