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
BIT SET
D7
D6
D5
D4
D3
D2
DESCRIPTION OF POSSIBLE
CAUSE
CONDITION DETECTED
DESCRIPTION OF
RESULTING DATA
Open RTD element
RTDIN+ shorted high and not
connected to RTD
Force+ shorted high and
connected to RTD
RTDIN+ shorted to RTDIN-
RTDIN+ shorted low and not
connected to RTD
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
Force- shorted high and not
connected to RTD
Force- shorted high and connected
to RTD
Force- shorted low and not
connected to RTD
Force- shorted low and connected
to RTD
RTDIN- shorted low and connected
to RTD
Force+ shorted low
RTDIN+ shorted low and
connected to RTD
RTDIN- shorted low and connected
to RTD
RTDIN- shorted low and not
connected to RTD
Force- shorted low
Overvoltage or undervoltage fault
Measured resistance greater than High Fault
Threshold value
Measured resistance less than Low Fault Threshold
value
VREFIN- > 0.85 x VBIAS
VREFIN- < 0.85 x VBIAS (FORCE- open)
VRTDIN- < 0.85 x VBIAS (FORCE- open)
Any protected input voltage >VDD or < GND1
Full scale
Near zero
Full scale
Indeterminate
Indeterminate
Appear to be valid
Near zero
Appear to be valid
Indeterminate
Maxim Integrated
22