LM32 National Semiconductor Corporation, LM32 Datasheet - Page 19

• Manufacturer Part Number: LM32
• Description: Dual Thermal Diode Temperature Sensor With SensorPath™ Bus
• Manufacturer: National Semiconductor Corporation

001 001
2.0 Register Set
2.9.3 Temperature Data Readout (Addr: 001 001; 09h)
All LM32 temperature data has a common format. The LM32’s temperature data format is two’s complement and has 10-bits of
resolution with the LSb having a weight of 0.5 ˚C. The LM32 can resolve temperature between +255.5 ˚C and -256 ˚C, inclusive.
It can measure local temperatures between +85 ˚C and 0 ˚C and remote temperatures between +125 ˚C and 0 ˚C with an
accuracy of
Reg
Add
15-6
Bit
3-2
5-4
0
1
Sensor Number
Register
Name
Local
Temperature
Data
Readout
Processor/
Remote
Temperature
Data
Readout
(SNUM)
Type
RO
RO
RO
RO
RO
0
1
2
±
3.0 ˚C.
Reserved. Will always read "0".
Reserved for Local Temperature Data Readout. Will always read "0".
EF (Error Flag) for Remote Temperature Data Readout. This bit indicates that an error was detected
during the measurement of the current remote Temperature sensor such as a diode fault condition. When a
diode fault occurs the value of the temperature reading will be 200h or -256˚C.
0: No error detected.
1: Error detected.
SNUM (Sensor Number). This field indicates the number of the current Temperature Sensor, to which the
data in the Temperature Readout field belongs. Temperature Sensor 0 is always assigned to the local
sensor of the LM32.
0: Local temperature sensor (see Table Thermal Diode Input Mapping)
1-2: Remote sensor 1 and 2 (see Table Thermal Diode Input Mapping)
Reserved. Will always read "0".
Temperature Readout. This field holds the result of the temperature measurement. The active size of this
field for the LM32 is 10-bits, left justified. See Table Temperature Data Format for examples.
Temperature
+140 ˚C
+100 ˚C
- 0.5 ˚C
+1 ˚C
-1 ˚C
0 ˚C
R/
W
R
Val
(Continued)
O
P
R
MSb
MSb
Sign
Bit
15
128
Bit
14
˚C
Processor, D1+/D1-
Remote, D2+/D2-
64˚C 32˚C 16˚C 8˚C 4˚C 2˚C 1˚C
Thermal Diode Input Mapping
Bit
13
Sensor Input
Temperature Data Format
Local
Bit
12
Bit
11
01 0001 1000
00 1100 1000
00 0000 0010
00 0000 0000
11 1111 1111
11 1111 1110
19
Description
Bit
Binary
10
Bit
9
Bit
8
Bit
7
Board Connection
none
CPU Thermal Diode
MMBT3904 Thermal Diode or GPU
Thermal Diode
Bit
0.5
˚C
6
Reserved
Reserved
Bit
5
0
0
Bit
4
0
0
0C8h
3FFh
3FEh
002h
000h
118h
Bit
Hex
3
SNUM
Bit
2
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Reserved
Bit
EF
1
0
LSb
Res
Bit
0
0
0