SE95 PHILIPS [NXP Semiconductors], SE95 Datasheet - Page 12

• Manufacturer Part Number: SE95
• Description: Ultra high accuracy digital temperature sensor and thermal WatchdogE
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
Table 6. Temp table
Obviously, for 9-bit Temp data application in replacing the industry standard LM75, just use only 9 MSB bits of the two bytes and disregard
7 LSB bits of the LS byte. The 9-bit temp data with 0.5 C resolution of the SE95 is defined exactly in the same way as for the standard LM75
and it is here similar to the Tos and Thyst that is described next.
Overtemp shut-down threshold (Tos) and hysteresis (Thyst) registers
These two registers are write/read registers, and also called set-point registers. They are used to store the user-defined temperature limits,
called overtemp shut-down threshold (Tos) and hysteresis (Thyst), for the device Watchdog operation. At the end of each conversion the Temp
data will be compared with the data stored in these two registers in order to set the state of the device OS output accordingly as described in the
“General operation” section.
Each of the set-point registers contains two 8-bit data bytes consisting of one MS data byte and one LS data byte the same as the Temp
register. However, only 9 bits of the two bytes are used to store the set-point data in 2’s complement format with the resolution of 0.5 C. The
Tos register table (Table 7) and Thyst register table (Table 8) show the bit arrangement of the Tos data and Thyst data in the data bytes.
Notice that because only 9-bit data are used in the set-point registers, the device uses only the 9 MSB bits of the Temp data for data
comparison.
Table 7. Tos register table
Table 8. Thyst register table
When a set-point register is read, all 16 bits are provided to the bus and must be collected by the controller to complete the bus operation.
However, only the 9 significant bits should be used and the 7 LSB bits of the LS byte are equal to zero and should be ignored.
The Tos and Thyst table (Table 9) shows examples of the limit data and value.
2004 Dec 21
11–bit Binary (2’s complement)
MSB
MSB
MSB
MSB
Ultra high accuracy digital temperature sensor and
thermal Watchdog
B7
D8
B7
D8
0001 1001 000
0000 0000 001
0000 0000 000
1100 1001 000
0111 1111 000
0111 1110 001
0111 1101 000
1110 0111 000
11001001 001
0111 1110 111
1111 1111 111
B6
D7
B6
D7
B5
D6
B5
D6
Thyst MS byte
Tos MS byte
B4
D5
B4
D5
Thyst data (9 bits)
Tos data (9 bits)
B3
D4
B3
D4
B2
D3
B2
D3
Temp data
3-bit Hex
3E8h
0C8h
7FFh
3F8h
3F7h
3F1h
001h
000h
738h
649h
648h
B1
D2
B1
D2
LSB
LSB
B0
D1
B0
D1
12
MSB
MSB
LSB
LSB
B7
D0
B7
D0
Decimal value
B6
B6
X
X
1016
1015
1009
1000
–200
–439
–440
200
–1
1
0
B5
B5
X
X
Thyst LS byte
Tos LS byte
B4
B4
X
X
Not used
Not used
B3
B3
X
X
+127.000 C
+126.875 C
+126.125 C
+125.000 C
Temp value
+25.000 C
–25.000 C
–54.875 C
–55.000 C
B2
B2
+0.125 C
–0.125 C
X
X
0.000 C
Product data sheet
C
B1
B1
X
X
SE95
LSB
LSB
B0
B0
X
X