19-5793; Rev 2; 2/12
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
General Description
The MAX31855 performs cold-junction compensation
and digitizes the signal from a K-, J-, N-, T-, S-, R-, or
E-type thermocouple. The data is output in a signed
14-bit, SPI-compatible, read-only format. This converter
resolves temperatures to 0.25NC, allows readings as high
as +1800NC and as low as -270NC, and exhibits thermocouple accuracy of ±2NC for temperatures ranging from
-200NC to +700NC for K-type thermocouples. For full
range accuracies and other thermocouple types, see the
Thermal Characteristics specifications.
Applications
Industrial
Appliances
HVAC
Automotive
V
CC
Features
S Cold-Junction Compensation
S 14-Bit, 0.25NC Resolution
S Versions Available for K-, J-, N-, T-, S-, R-, and
E-Type Thermocouples (see Table 1)
S Simple SPI-Compatible Interface (Read-Only)
S Detects Thermocouple Shorts to GND or V
CC
S Detects Open Thermocouple
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to: www.maxim-ic.com/MAX31855.related
Typical Application Circuit
0.1µF
MAX31855
GND
SO
T+
T-
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SCK
CS
MICROCONTROLLER
MISO
SCK
SS
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
ABSOLUTE MAXIMUM RATINGS
Supply Voltage Range (VCC to GND) .................. -0.3V to +4.0V
All Other Pins ............................................ -0.3V to (VCC + 0.3V)
Continuous Power Dissipation (TA = +70NC)
SO (derate 5.9mW/NC above +70NC) .......................470.6mW
ESD Protection (All Pins, Human Body Model) ...................±2kV
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
SO
Junction-to-Ambient Thermal Resistance (BJA) ........170NC/W
Junction-to-Case Thermal Resistance (BJC) ...............40NC/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
RECOMMENDED OPERATING CONDITIONS
(TA = -40NC to +125NC, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Supply Voltage V
Input Logic 0 V
Input Logic 1 V
CC
(Note 2) 3.0 3.3 3.6 V
IL
IH
Operating Temperature Range ........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range .......................... -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) .....................................+260NC
-0.3 +0.8 V
2.1
VCC +
0.3
V
DC ELECTRICAL CHARACTERISTICS
(3.0V P VCC P 3.6V, TA = -40NC to +125NC, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Supply Current I
Thermocouple Input Bias Current
Power-Supply Rejection -0.3
Power-On Reset Voltage
Threshold
Power-On Reset Voltage
Hysteresis
Output High Voltage V
Output Low Voltage V
����������������������������������������������������������������� Maxim Integrated Products 2
V
CC
POR
OH
OL
TA = -40NC to +125NC, 100mV across the
thermocouple inputs
(Note 3) 2 2.5 V
I
= -1.6mA
OUT
I
= 1.6mA 0.4 V
OUT
-100 +100 nA
VCC -
0.4
900 1500
NC/V
0.2 V
FA
V
Cold-Junction Compensated
Thermocouple-to-Digital Converter
THERMAL CHARACTERISTICS
(3.0V P VCC P 3.6V, TA = -40NC to +125NC, unless otherwise noted.) (Note 4)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX31855K Thermocouple
Temperature Gain and Offset
Error (41.276FV/NC nominal
sensitivity) (Note 4)
MAX31855J Thermocouple
Temperature Gain and Offset
Error (57.953FV/NC nominal
sensitivity) (Note 4)
MAX31855N Thermocouple
Temperature Gain and Offset
Error (36.256FV/NC nominal
sensitivity) (Note 4)
MAX31855T Thermocouple
Temperature Gain and Offset
Error (52.18FV/NC nominal
sensitivity) (Note 4)
MAX31855E Thermocouple
Temperature Gain and Offset
Error (76.373FV/NC nominal
sensitivity) (Note 4)
MAX31855R Thermocouple
Temperature Gain and Offset
Error (10.506FV/NC nominal
sensitivity) (Note 4)
MAX31855S Thermocouple
Temperature Gain and Offset
Error (9.587FV/NC nominal
sensitivity) (Note 4)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -40NC to +125NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -40NC to +125NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -40NC to +125NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -40NC to +125NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -40NC to +125NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -40NC to +125NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -20NC to +85NC (Note 3)
T
THERMOCOUPLE
TA = -40NC to +125NC (Note 3)
= -200NC to +700NC,
= +700NC to +1350NC,
= -270NC to +1372NC,
= -210NC to +750NC,
= -210NC to +1200NC,
= -200NC to +700NC,
= +700NC to +1300NC,
= -270NC to +1300NC,
= -270NC to +400NC,
= -270NC to +400NC,
= -200NC to +700NC,
= +700NC to +1000NC,
= -270NC to +1000NC,
= -50NC to +700NC,
= +700NC to +1768NC,
= -50NC to +1768NC,
= -50NC to +700NC,
= +700NC to +1768NC,
= -50NC to +1768NC,
MAX31855
-2 +2
-4 +4
-6 +6
-2 +2
-4 +4
-2 +2
-4 +4
-6 +6
-2 +2
-4 +4
-2 +2
-3 +3
-5 +5
-2 +2
-4 +4
-6 +6
-2 +2
-4 +4
-6 +6
NC
NC
NC
NC
NC
NC
NC
����������������������������������������������������������������� Maxim Integrated Products 3
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
THERMAL CHARACTERISTICS (continued)
(3.0V P VCC P 3.6V, TA = -40NC to +125NC, unless otherwise noted.) (Note 4)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Thermocouple Temperature Data
Resolution
Internal Cold-Junction
Temperature Error
Cold-Junction Temperature Data
Resolution
Temperature Conversion Time
(Thermocouple, Cold Junction,
Fault Detection)
Thermocouple Conversion
Power-Up Time
t
CONV
t
CONV_PU
TA = -20NC to +85NC (Note 3)
TA = -40NC to +125NC (Note 3)
TA = -40NC to +125NC
(Note 5) 70 100 ms
(Note 6) 200 ms
-2 +2
-3 +3
SERIAL-INTERFACE TIMING CHARACTERISTICS
(See Figure 1 and Figure 2.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Leakage Current I
Input Capacitance C
Serial-Clock Frequency f
SCK Pulse-High Width t
SCK Pulse-Low Width t
SCK Rise and Fall Time 200 ns
CS Fall to SCK Rise
SCK to CS Hold
CS Fall to Output Enable
CS Rise to Output Disable
SCK Fall to Output Data Valid t
CS Inactive Time
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 TA = +25NC. Specification limits over temperature (TA = T
design and characterization; not production tested.
Note 6: Because the thermocouple temperature conversions begin at V
temperature conversion may not produce an accurate result. Therefore, the t
greater than V
Note 7: For all pins except T+ and T- (see the Thermocouple Input Bias Current parameter in the DC Electrical Characteristics
table).
to guarantee a valid thermocouple temperature conversion result.
CCMIN
LEAK
SCL
CH
CL
t
CSS
t
DV
t
TR
DO
(Note 7) -1 +1 µA
IN
100 ns
100 ns
100 ns
100 ns
(Note 3) 200 ns
, depending on VCC slew rates, the first thermocouple
POR
CONV_PU
specification is required after VCC is
MIN
0.25
0.0625
8 pF
to T
) are guaranteed by
MAX
NC
NC
NC
5 MHz
100 ns
40 ns
40 ns
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CS
SCK
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Serial-Interface Diagrams
SO
D31
Figure 1. Serial-Interface Protocol
t
CSS
CS
SCK
t
DV
SO
D31 D0D1D2D3
Figure 2. Serial-Interface Timing
D7 D6
D8
t
CH
t
DO
t
CL
D4
D5
D2
D3
t
TR
D0
D1
����������������������������������������������������������������� Maxim Integrated Products 5
Thermocouple-to-Digital Converter
06
06
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
MAX31855
Cold-Junction Compensated
Typical Operating Characteristics
SUPPLY CURRENT vs. TEMPERATURE
1.4
VCC = 3.6V
1.2
1.0
0.8
0.6
SUPPLY CURRENT (mA)
0.4
0.2
0
-40
VCC = 3.0V
TEMPERATURE (°C)
VCC = 3.3V
ADC ACCURACY vs. ADC INPUT VOLTAGE
ACROSS TEMPERATURE
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
ADC ACCURACY (°C)
-0.4
-0.5
-0.6
VCC = 3.3V
-0.7
AT -40°C
AT +85°C
AT +25°C
4020
ADC INPUT VOLTAGE (mV)
INTERNAL TEMPERATURE SENSOR
ACCURACY
0.7
VCC = 3.3V
0.6
MAX31855 toc01
100 120806040200-20
0.5
0.4
0.3
0.2
0.1
MEASUREMENT ERROR (°C)
0
-0.1
-0.2
NOTE: THIS DATA WAS TAKEN
IN PRECISION BATH SO HIGH
TEMPERATURE LIMIT IS 90°C
-40 100
TEMPERATURE (°C)
MAX31855 toc02
806020 400-20
ADC ACCURACY vs. ADC INPUT VOLTAGE
MAX31855 toc03
0
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
ADC ACCURACY (°C)
-0.7
-0.8
-0.9
-1.0
VCC = 3.3V
INTERNAL TEMPERATURE = +25°C
ADC INPUT VOLTAGE (mV)
ACROSS V
VCC = 3.6V
CC
VCC = 3.0V
4020
MAX31855 toc04
0
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MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
TOP VIEW
GND
T+
CC
Pin Configuration
Pin Description
PIN NAME FUNCTION
1 GND Ground
+
1
2
MAX31855
3
4
87DNC
SOT-
CS
6
SCKV
5
2 T-
3 T+ Thermocouple Input. See Table 1.
4 V
5 SCK Serial-Clock Input
6
CS
Thermocouple Input. See Table 1. Do
not connect to GND.
Power-Supply Voltage
CC
Active-Low Chip Select. Set CS low to
enable the serial interface.
7 SO Serial-Data Output
SO
8 DNC Do Not Connect
Block Diagram
V
CC
V
CC
SCK
SO
CS
MAX31855
COLD-JUNCTION
COMPENSATION
S5
DIGITAL
CONTROL
T+
T-
S1
S2
S3
FAULT
DETECTION
S4
ADC
GND
REFERENCE
VOLTAGE
����������������������������������������������������������������� Maxim Integrated Products 7
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Detailed Description
The MAX31855 is a sophisticated thermocouple-todigital converter with a built-in 14-bit analog-to-digital
converter (ADC). The device also contains cold-junction
compensation sensing and correction, a digital controller, an SPI-compatible interface, and associated control
logic. The device is designed to work in conjunction
with an external microcontroller (FC) in thermostatic,
process-control, or monitoring applications. The device
is available in several versions, each optimized and
trimmed for a specific thermocouple type (K, J, N, T, S,
R, or E.). The thermocouple type is indicated in the suffix
of the part number (e.g., MAX31855K). See the Ordering
Information table for all options.
Temperature Conversion
The device includes signal-conditioning hardware to
convert the thermocouple’s signal into a voltage compatible with the input channels of the ADC. The T+ and
T- inputs connect to internal circuitry that reduces the
introduction of noise errors from the thermocouple wires.
Before converting the thermoelectric voltages into equivalent temperature values, it is necessary to compensate
for the difference between the thermocouple coldjunction side (device ambient temperature) and a 0NC
virtual reference. For a K-type thermocouple, the voltage changes by about 41FV/NC, which approximates
the thermocouple characteristic with the following linear
equation:
V
where V
= (41.276FV/NC) x (TR - T
OUT
is the thermocouple output voltage (FV), TR
OUT
AMB
)
is the temperature of the remote thermocouple junction
(NC), and T
is the temperature of the device (NC).
AMB
Other thermocouple types use a similar straight-line
approximation but with different gain terms. Note that the
MAX31855 assumes a linear relationship between temperature and voltage. Because all thermocouples exhibit
some level of nonlinearity, apply appropriate correction
to the device’s output data.
Cold-Junction Compensation
The function of the thermocouple is to sense a difference
in temperature between two ends of the thermocouple
wires. The thermocouple’s “hot” junction can be read
across the operating temperature range (Table 1). The
reference junction, or “cold” end (which should be at
Table 1. Thermocouple Wire Connections and Nominal Sensitivities
TYPE T- WIRE T+ WIRE
K
J
N
S
T
E
R
Alumel Chromel -270 to +1372
Constantan Iron -210 to +1200
Nisil Nicrosil -270 to + 1300
Platinum
Constantan Copper -270 to +400
Constantan Chromel -270 to +1000
Platinum Platinum/Rhodium -50 to +1768
Platinum/Rhodium
TEMP RANGE (°C) SENSITIVITY (µV/°C)
41.276
(0NC to +1000NC)
57.953
(0NC to +750NC)
36.256
(0NC to +1000NC)
+50 to +1768
9.587
(0NC to +1000NC)
52.18
(0NC to +400NC)
76.373
(0NC to +1000NC)
10.506
(0NC to +1000NC)
COLD-JUNCTION
SENSITIVITY (µV/°C)
(0NC TO +70NC)
40.73
52.136
27.171
6.181
41.56
44.123
6.158
����������������������������������������������������������������� Maxim Integrated Products 8
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
the same temperature as the board on which the device
is mounted) can range from -55NC to +125NC. While the
temperature at the cold end fluctuates, the device continues to accurately sense the temperature difference at
the opposite end.
The device senses and corrects for the changes in
the reference junction temperature with cold-junction
compensation. It does this by first measuring its internal
die temperature, which should be held at the same temperature as the reference junction. It then measures the
voltage from the thermocouple’s output at the reference
junction and converts this to the noncompensated thermocouple temperature value. This value is then added
to the device’s die temperature to calculate the thermocouple’s “hot junction” temperature. Note that the “hot
junction” temperature can be lower than the cold junction
(or reference junction) temperature.
Optimal performance from the device is achieved when
the thermocouple cold junction and the device are at
the same temperature. Avoid placing heat-generating
devices or components near the MAX31855 because this
could produce cold-junction-related errors.
Conversion Functions
During the conversion time, t
performed: the temperature conversion of the internal
cold-junction temperature, the temperature conversion of
the external thermocouple, and the detection of thermocouple faults.
When executing the temperature conversion for the internal cold-junction compensation circuit, the connection to
signal from the external thermocouple is opened (switch
S4) and the connection to the cold-junction compensation circuit is closed (switch S5). The internal T- reference
to ground is still maintained (switch S3 is closed) and
the connections to the fault-detection circuit are open
(switches S1 and S2).
When executing the temperature conversion of the
external thermocouple, the connections to the internal
fault-detection circuit are opened (switches S1 and S2 in
the Block Diagram) and the switch connecting the coldjunction compensation circuit is opened (switch S5). The
internal ground reference connection (switch S3) and
the connection to the ADC (switch S4) are closed. This
allows the ADC to process the voltage detected across
the T+ and T- terminals.
, three functions are
CONV
During fault detection, the connections from the external thermocouple and cold-junction compensation circuit to the ADC are opened (switches S4 and S5). The
internal ground reference on T- is also opened (switch
S3). The connections to the internal fault-detection circuit are closed (switch S1 and S2). The fault-detection
circuit tests for shorted connections to VCC or GND on
the T+ and T- inputs, as well as looking for an open
thermocouple condition. Bits D0, D1, and D2 of the
output data are normally low. Bit D2 goes high to indicate a thermocouple short to VCC, bit D1 goes high to
indicate a thermocouple short to GND, and bit D0 goes
high to indicate a thermocouple open circuit. If any of
these conditions exists, bit D16 of the SO output data,
which is normally low, also goes high to indicate that a
fault has occurred.
Serial Interface
The Typical Application Circuit shows the device interfaced with a microcontroller. In this example, the device
processes the reading from the thermocouple and
transmits the data through a serial interface. Drive CS
low and apply a clock signal at SCK to read the results
at SO. Conversions are always being performed in the
background. The fault and temperature data are only be
updated when CS is high.
Drive CS low to output the first bit on the SO pin. A
complete serial-interface read of the cold-junction compensated thermocouple temperature requires 14 clock
cycles. Thirty-two clock cycles are required to read both
the thermocouple and reference junction temperatures
(Table 2 and Table 3.) The first bit, D31, is the thermocouple temperature sign bit, and is presented to the SO
pin within tDV of the falling edge of CS. Bits D[30:18]
contain the converted temperature in the order of MSB
to LSB, and are presented to the SO pin within tD0 of the
falling edge of SCK. Bit D16 is normally low and goes
high when the thermocouple input is open or shorted to
GND or VCC. The reference junction temperature data
begins with D15. CS can be taken high at any point while
clocking out conversion data. If T+ and T- are unconnected, the thermocouple temperature sign bit (D31) is
0, and the remainder of the thermocouple temperature
value (D[30:18]) is 1.
Figure 1 and Figure 2 show the serial-interface timing
and order. Table 2 and Table 3 show the SO output bit
weights and functions.
����������������������������������������������������������������� Maxim Integrated Products 9
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Table 2. Memory Map—Bit Weights and Functions
MAX31855
BIT
VALUE
14-BIT THERMOCOUPLE
TEMPERATURE DATA
D31 D30 … D18 D17 D16 D15 D14 … D4 D3 D2 D1 D0
Sign
MSB 210
(1024NC)
LSB 2
…
(0.25NC)
-2
RES
Reserved
FAULT
BIT
1 =
Fault
12-BIT INTERNAL TEMPERATURE
DATA
Sign
MSB
6
2
(64NC)
…
-4
LSB 2
(0.0625NC)
RES
Reserved
SCV
BIT
1 =
Short
to
V
CC
Table 3. Memory Map—Descriptions
BIT NAME DESCRIPTION
D[31:18]
D17 Reserved This bit always reads 0.
D16 Fault
D[15:4]
D3 Reserved This bit always reads 0.
D2 SCV Fault This bit is a 1 when the thermocouple is short-circuited to VCC. Default value is 0.
D1 SCG Fault This bit is a 1 when the thermocouple is short-circuited to GND. Default value is 0.
D0 OC Fault This bit is a 1 when the thermocouple is open (no connections). Default value is 0.
14-Bit Thermocouple
Temperature Data
12-Bit Internal Temperature
Data
These bits contain the signed 14-bit thermocouple temperature value. See Table 4.
This bit reads at 1 when any of the SCV, SCG, or OC faults are active. Default value
is 0.
These bits contain the signed 12-bit value of the reference junction temperature.
See Table 5.
SCG
BIT
1 =
Short
to
GND
OC
BIT
1 =
Open
Circuit
Table 4. Thermocouple Temperature Data Format
TEMPERATURE
(NC)
+1600.00 0110 0100 0000 00
+1000.00 0011 1110 1000 00
+100.75 0000 0110 0100 11
+25.00 0000 0001 1001 00
0.00 0000 0000 0000 00
-0.25 1111 1111 1111 11
-1.00 1111 1111 1111 00
-250.00 1111 0000 0110 00
Note: The practical temperature ranges vary with the
thermocouple type.
���������������������������������������������������������������� Maxim Integrated Products 10
DIGITAL OUTPUT
(D[31:18])
Table 5. Reference Junction Temperature Data Format
TEMPERATURE
(NC)
+127.0000 0111 1111 0000
+100.5625 0110 0100 1001
+25.0000 0001 1001 0000
0.0000 0000 0000 0000
-0.0625 1111 1111 1111
-1.0000 1111 1111 0000
-20.0000 1110 1100 0000
-55.0000 1100 1001 0000
DIGITAL OUTPUT
(D[15:4])
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Applications Information
Noise Considerations
Because of the small signal levels involved, thermocouple temperature measurement is susceptible to powersupply coupled noise. The effects of power-supply noise
can be minimized by placing a 0.1FF ceramic bypass
capacitor close to the VCC pin of the device and to GND.
The input amplifier is a low-noise amplifier designed to
enable high-precision input sensing. Keep the thermocouple and connecting wires away from electrical noise
sources. It is strongly recommended to add a 10nF
ceramic surface-mount differential capacitor, placed
across the T+ and T- pins, in order to filter noise on the
thermocouple lines.
Thermal Considerations
Self-heating degrades the device’s temperature measurement accuracy in some applications. The magnitude of the
temperature errors depends on the thermal conductivity
of the device package, the mounting technique, and the
effects of airflow. Use a large ground plane to improve the
device’s temperature measurement accuracy.
The thermocouple system’s accuracy can also be
improved by following these precautions:
• Usethelargestwirepossiblethatdoesnotshuntheat
away from the measurement area.
• If a small wire is required, use it only in the region
of the measurement, and use extension wire for the
region with no temperature gradient.
• Avoidmechanical stress and vibration, which could
strain the wires.
• Whenusinglong thermocouple wires, use a twisted
pair extension wire.
• Avoidsteeptemperaturegradients.
• Tryto use the thermocouple wire well withinitstem-
perature rating.
• Usethe propersheathingmaterialin hostile environments to protect the thermocouple wire.
• Useextensionwireonlyatlowtemperaturesandonly
in regions of small gradients.
• Keepaneventlogandacontinuousrecordofthermocouple resistance.
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Cold-Junction Compensated
Thermocouple-to-Digital Converter
PART THERMOCOUPLE TYPE MEASURED TEMP RANGE PIN-PACKAGE
MAX31855KASA+ K
MAX31855KASA+T K
MAX31855JASA+ J
MAX31855JASA+T J
MAX31855NASA+ N
MAX31855NASA+T N
MAX31855SASA+ S
MAX31855SASA+T S
MAX31855TASA+ T
MAX31855TASA+T T
MAX31855EASA+ E
MAX31855EASA+T E
MAX31855RASA+ R
MAX31855RASA+T R
Note: All devices are specified over the -40°C to +125°C operating temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
-200NC to +1350NC
-200NC to +1350NC
-40NC to +750NC
-40NC to +750NC
-200NC to + 1300NC
-200NC to + 1300NC
+50NC to +1600NC
+50NC to +1600NC
-250NC to +400NC
-250NC to +400NC
-40NC to +900NC
-40NC to +900NC
-50NC to +1770NC
-50NC to +1770NC
MAX31855
Ordering Information
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
8 SO
Package Information
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
8 SO S8+4
21-0041 90-0096
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MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Revision History
REVISION
NUMBER
0 3/11 Initial release —
1 11/11 Corrected ESD protection value; added “S” and “R” type specifications 1, 2, 3, 8, 12
2 2/12
REVISION
DATE
DESCRIPTION
Corrected the thermocouple temperature conditions in the Thermal Characteristics
table and Table 1; added clarification to the Serial Interface section to help users
better understand how to communicate with the device; added a recommendation to
add a 10nF differential capacitor to the T+/T- pins in the Noise Considerations section
CHANGED
PAGES
3, 8, 9, 11
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 13
©
2012 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
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