MAX31865
RTD-to-Digital Converter
Table 12. Decoding RTD Faults for 4-Wire Setups When Fault Bit in RTD Data LSB
Register = 1
FAULT
STATUS
BꢀT SET
DESCRꢀPTꢀON OF POSSꢀBLE
CAUSE
DESCRꢀPTꢀON OF
RESULTꢀNG DATA
CONDꢀTꢀON DETECTED
Open RTD element
RTDIN+ shorted high and not
connected to RTD
Measured resistance greater than High Fault
Threshold value
D7
D6
Full scale
Force+ shorted high and
connected to RTD
RTDIN+ shorted to RTDIN-
RTDIN+ shorted low and not
connected to RTD
Measured resistance less than Low Fault Threshold
value
Near zero
Full scale
RTDIN- shorted high and not
connected to RTD
Force+ shorted low
Open RTD element
Force+ shorted high and
connected to RTD
Force- unconnected
Force+ unconnected
Force+ shorted high and not
connected to RTD
D5
V
- > 0.85 x V
REFIN BIAS
Force- shorted high and not
connected to RTD
Indeterminate
Force- shorted high and connected
to RTD
Force- shorted low and not
connected to RTD
Force- shorted low and connected
to RTD
Indeterminate
D4
V
V
- < 0.85 x V
(FORCE- open)
(FORCE- open)
REFIN
BIAS
RTDIN- shorted low and connected
to RTD
Appear to be valid
Force+ shorted low
Near zero
RTDIN+ shorted low and
connected to RTD
RTDIN- shorted low and connected
to RTD
D3
D2
- < 0.85 x V
BIAS
RTDIN
Appear to be valid
Indeterminate
RTDIN- shorted low and not
connected to RTD
Force- shorted low
Overvoltage or undervoltage fault
Any protected input voltage >V
or < GND1
DD
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