Rainbow Electronics LM41 - Manual (Page 20)

2.0 Register Set
(Continued)
2.9.3 Temperature Data Readout (Addr: 001 001; 09h)
Reg
Add
Register
Name
R/
W
P
O
R
Val
Bit
15
MSb
Bit
14
Bit
13
Bit
12
Bit
11
Bit
10
Bit
9
Bit
8
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
LSb
001 001
Local
Temperature
Data
Readout
R
MSb
Sign
128
˚C
64˚C 32˚C 16˚C 8˚C 4˚C 2˚C 1˚C
0.5
˚C
Reserved
S
NUM
Reserved
0 0 0 0 0
Processor/
Remote
Temperature
Data
Readout
Reserved
EF
Res
0 0 0 0
Bit Type Description
0 RO Reserved. Will always read "0".
1 RO 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.
2 RO 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 LM41.
0: Local temperature sensor (see Table Thermal Diode Input Mapping)
1: Remote sensor (see Table Thermal Diode Input Mapping)
5-3 RO Reserved. Will always read "0".
15-6 RO Temperature Readout. This field holds the result of the temperature measurement. The active size of this
field for the LM41 is 10-bits, left justified. See Table Temperature Data Format for examples.
Thermal Diode Input Mapping
Sensor Number
(SNUM) Sensor Input Board Connection
0 Local none
1 Processor, D+/D- CPU Thermal Diode, MMBT3904
Thermal Diode or GPU Thermal Diode
All LM41 temperature data has a common format. The LM41’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 LM41 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
± 3.0 ˚C.
Temperature Data Format
Temperature Binary Hex
+140 ˚C 01 0001 1000 118h
+100 ˚C 00 1100 1000 0C8h
+1 ˚C 00 0000 0010 002h
0 ˚C 00 0000 0000 000h
- 0.5 ˚C 11 1111 1111 3FFh
-1 ˚C 11 1111 1110 3FEh
- 40 ˚C 11 1011 0000 3B0h
LM41
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