MAX31865
RTD-to-Digital Converter
resistance to reference resistance. D0 of the RTD LSBs
register is a Fault bit that indicates whether any RTD
faults have been detected.
RTD Resistance Registers (01h−02h)
Two 8-bit registers, RTD MSBs and RTD LSBs, contain
the RTD resistance data. The data format is shown in
Table 4. The data format is simply the 15-bit ratio of RTD
Table 4. RTD Resistance Registers Definition
REGꢀSTER
RTD MSBS (01h) REGꢀSTER
RTD LSBS (02h) REGꢀSTER
Bit
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
RTD
Resistance MSB
Data
—
—
—
—
—
—
—
—
—
—
—
—
—
LSB Fault
Bit
Weighting
214
213
212
211
210
29
28
27
26
25
24
23
8
22
4
21
2
20
1
—
—
Decimal
Value
16384 8192 4096 2048 1024 512
256
128
64
32
16
Table 5. RTD Resistance-Data Relationship
BꢀNARY
HEX
R
/R
DECꢀMAL
RTD REF
RTD MSBs (01h)
0000 0110
0010 0000
0100 0000
1000 0000
1100 0000
1111 1111
RTD LSBs (02h)
0110 0110b
0000 0000b
0000 0000b
0000 0000b
0000 0000b
1111 1110b
RTD MSBs (01h)
RTD LSBs (02h)
0.025
0.125
0.25
06h
20h
40h
80h
C0h
FFh
66h
00h
00h
00h
00h
FEh
819
4096
8192
0.50
16,384
24,576
32,767
0.75
0.999
Note: D0 (“Fault”) is assumed to be 0.
Maxim Integrated
14
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
