Datasheet
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MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Note 2: All voltages are referenced to GND. Currents entering the IC are specified positive, and currents exiting the IC are negative.
Note 3: Guaranteed by design; not production tested.
Note 4: Not including cold-junction temperature error or thermocouple nonlinearity.
Note 5: Specification is 100% tested at T
A
= +25NC. Specification limits over temperature (T
A
= T
MIN
to T
MAX
) are guaranteed by
design and characterization; not production tested.
Note 6: Because the thermocouple temperature conversions begin at V
POR
, depending on V
CC
slew rates, the first thermocouple
temperature conversion may not produce an accurate result. Therefore, the t
CONV_PU
specification is required after V
CC
is
greater than V
CCMIN
to guarantee a valid thermocouple temperature conversion result.
Note 7: For all pins except T+ and T- (see the Thermocouple Input Bias Current parameter in the DC Electrical Characteristics
table).
SERIAL-INTERFACE TIMING CHARACTERISTICS
(See Figure 1 and Figure 2.)
THERMAL CHARACTERISTICS (continued)
(3.0V P V
CC
P 3.6V, T
A
= -40NC to +125NC, unless otherwise noted.) (Note 4)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Leakage Current I
LEAK
(Note 7) -1 +1 µA
Input Capacitance C
IN
8 pF
Serial-Clock Frequency f
SCL
5 MHz
SCK Pulse-High Width t
CH
100 ns
SCK Pulse-Low Width t
CL
100 ns
SCK Rise and Fall Time 200 ns
CS Fall to SCK Rise
t
CSS
100 ns
SCK to CS Hold
100 ns
CS Fall to Output Enable
t
DV
100 ns
CS Rise to Output Disable
t
TR
40 ns
SCK Fall to Output Data Valid t
DO
40 ns
CS Inactive Time
(Note 3) 200 ns
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Thermocouple Temperature Data
Resolution
0.25
NC
Internal Cold-Junction
Temperature Error
T
A
= -20NC to +85NC (Note 3)
-2 +2
NC
T
A
= -40NC to +125NC (Note 3)
-3 +3
Cold-Junction Temperature Data
Resolution
T
A
= -40NC to +125NC
0.0625
NC
Temperature Conversion Time
(Thermocouple, Cold Junction,
Fault Detection)
t
CONV
(Note 5) 70 100 ms
Thermocouple Conversion
Power-Up Time
t
CONV_PU
(Note 6) 200 ms