AVAILABLE
Functional Diagrams
Pin Configurations appear at end of data sheet.
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
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 thermo-
couple 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
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 VCC
S Detects Open Thermocouple
Typical Application Circuit
19-5793; Rev 2; 2/12
For related parts and recommended products to use with this part,
refer to: www.maxim-ic.com/MAX31855.related
Ordering Information appears at end of data sheet.
VCC
GND
T+
T-
SO
SCK
CS
MICROCONTROLLER
MISO
SCK
SS
0.1µF
MAX31855
MAX31855
Cold-Junction Compensated
Thermocouple-to-Digital Converter
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
Operating Temperature Range ........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range .......................... -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) .....................................+260NC
SO
Junction-to-Ambient Thermal Resistance (BJA) ........170NC/W
Junction-to-Case Thermal Resistance (BJC) ...............40NC/W
ABSOLUTE MAXIMUM RATINGS
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.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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)
RECOMMENDED OPERATING CONDITIONS
(TA = -40NC to +125NC, unless otherwise noted.)
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 Voltage VCC (Note 2) 3.0 3.3 3.6 V
Input Logic 0 VIL -0.3 +0.8 V
Input Logic 1 VIH 2.1 VCC +
0.3 V
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Supply Current ICC 900 1500 FA
Thermocouple Input Bias Current TA = -40NC to +125NC, 100mV across the
thermocouple inputs -100 +100 nA
Power-Supply Rejection -0.3 NC/V
Power-On Reset Voltage
Threshold VPOR (Note 3) 2 2.5 V
Power-On Reset Voltage
Hysteresis 0.2 V
Output High Voltage VOH IOUT = -1.6mA VCC -
0.4 V
Output Low Voltage VOL IOUT = 1.6mA 0.4 V
MAX31855
Maxim Integrated
2
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)
TTHERMOCOUPLE = -200NC to +700NC,
TA = -20NC to +85NC (Note 3) -2 +2
NC
TTHERMOCOUPLE = +700NC to +1350NC,
TA = -20NC to +85NC (Note 3) -4 +4
TTHERMOCOUPLE = -270NC to +1372NC,
TA = -40NC to +125NC (Note 3) -6 +6
MAX31855J Thermocouple
Temperature Gain and Offset
Error (57.953FV/NC nominal
sensitivity) (Note 4)
TTHERMOCOUPLE = -210NC to +750NC,
TA = -20NC to +85NC (Note 3) -2 +2
NC
TTHERMOCOUPLE = -210NC to +1200NC,
TA = -40NC to +125NC (Note 3) -4 +4
MAX31855N Thermocouple
Temperature Gain and Offset
Error (36.256FV/NC nominal
sensitivity) (Note 4)
TTHERMOCOUPLE = -200NC to +700NC,
TA = -20NC to +85NC (Note 3) -2 +2
NC
TTHERMOCOUPLE = +700NC to +1300NC,
TA = -20NC to +85NC (Note 3) -4 +4
TTHERMOCOUPLE = -270NC to +1300NC,
TA = -40NC to +125NC (Note 3) -6 +6
MAX31855T Thermocouple
Temperature Gain and Offset
Error (52.18FV/NC nominal
sensitivity) (Note 4)
TTHERMOCOUPLE = -270NC to +400NC,
TA = -20NC to +85NC (Note 3) -2 +2
NC
TTHERMOCOUPLE = -270NC to +400NC,
TA = -40NC to +125NC (Note 3) -4 +4
MAX31855E Thermocouple
Temperature Gain and Offset
Error (76.373FV/NC nominal
sensitivity) (Note 4)
TTHERMOCOUPLE = -200NC to +700NC,
TA = -20NC to +85NC (Note 3) -2 +2
NC
TTHERMOCOUPLE = +700NC to +1000NC,
TA = -20NC to +85NC (Note 3) -3 +3
TTHERMOCOUPLE = -270NC to +1000NC,
TA = -40NC to +125NC (Note 3) -5 +5
MAX31855R Thermocouple
Temperature Gain and Offset
Error (10.506FV/NC nominal
sensitivity) (Note 4)
TTHERMOCOUPLE = -50NC to +700NC,
TA = -20NC to +85NC (Note 3) -2 +2
NC
TTHERMOCOUPLE = +700NC to +1768NC,
TA = -20NC to +85NC (Note 3) -4 +4
TTHERMOCOUPLE = -50NC to +1768NC,
TA = -40NC to +125NC (Note 3) -6 +6
MAX31855S Thermocouple
Temperature Gain and Offset
Error (9.587FV/NC nominal
sensitivity) (Note 4)
TTHERMOCOUPLE = -50NC to +700NC,
TA = -20NC to +85NC (Note 3) -2 +2
NC
TTHERMOCOUPLE = +700NC to +1768NC,
TA = -20NC to +85NC (Note 3) -4 +4
TTHERMOCOUPLE = -50NC to +1768NC,
TA = -40NC to +125NC (Note 3) -6 +6
MAX31855
Maxim Integrated
3
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 TA = +25NC. Specification limits over temperature (TA = TMIN to TMAX) are guaranteed by
design and characterization; not production tested.
Note 6: Because the thermocouple temperature conversions begin at VPOR, depending on VCC slew rates, the first thermocouple
temperature conversion may not produce an accurate result. Therefore, the tCONV_PU specification is required after VCC is
greater than VCCMIN 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 VCC P 3.6V, TA = -40NC to +125NC, unless otherwise noted.) (Note 4)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Leakage Current ILEAK (Note 7) -1 +1 µA
Input Capacitance CIN 8 pF
Serial-Clock Frequency fSCL 5 MHz
SCK Pulse-High Width tCH 100 ns
SCK Pulse-Low Width tCL 100 ns
SCK Rise and Fall Time 200 ns
CS Fall to SCK Rise tCSS 100 ns
SCK to CS Hold 100 ns
CS Fall to Output Enable tDV 100 ns
CS Rise to Output Disable tTR 40 ns
SCK Fall to Output Data Valid tDO 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
TA = -20NC to +85NC (Note 3) -2 +2 NC
TA = -40NC to +125NC (Note 3) -3 +3
Cold-Junction Temperature Data
Resolution TA = -40NC to +125NC0.0625 NC
Temperature Conversion Time
(Thermocouple, Cold Junction,
Fault Detection)
tCONV (Note 5) 70 100 ms
Thermocouple Conversion
Power-Up Time tCONV_PU (Note 6) 200 ms
MAX31855
Maxim Integrated
4
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Serial-Interface Diagrams
Figure 1. Serial-Interface Protocol
Figure 2. Serial-Interface Timing
CS
SCK
SO D31 D8 D7 D6 D5 D4 D3 D2 D1
D0
D31 D0D1D2D3
SCK
SO
tDV
tCSS
tDO
CS
tTR
tCH tCL
MAX31855
Maxim Integrated
5
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Typical Operating Characteristics
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
ADC ACCURACY vs. ADC INPUT VOLTAGE
ACROSS VCC
MAX31855 toc04
ADC INPUT VOLTAGE (mV)
ADC ACCURACY (°C)
4020
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
-1.0
06
0
VCC = 3.6V
VCC = 3.3V
VCC = 3.0V
INTERNAL TEMPERATURE = +25°C
ADC ACCURACY vs. ADC INPUT VOLTAGE
ACROSS TEMPERATURE
MAX31855 toc03
ADC INPUT VOLTAGE (mV)
ADC ACCURACY (°C)
4020
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
-0.7
06
0
AT -40°C
VCC = 3.3V
AT +85°C
AT +25°C
INTERNAL TEMPERATURE SENSOR
ACCURACY
MAX31855 toc02
TEMPERATURE (°C)
MEASUREMENT ERROR (°C)
806020 400-20
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
-0.2
-40 100
VCC = 3.3V
NOTE: THIS DATA WAS TAKEN
IN PRECISION BATH SO HIGH
TEMPERATURE LIMIT IS 90°C
SUPPLY CURRENT vs. TEMPERATURE
MAX31855 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
100 120806040200-20
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0
-40
VCC = 3.6V
VCC = 3.3V
VCC = 3.0V
MAX31855
Maxim Integrated
6
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Pin Description
Pin Configuration
Block Diagram
PIN NAME FUNCTION
1 GND Ground
2 T- Thermocouple Input. See Table 1. Do
not connect to GND.
3 T+ Thermocouple Input. See Table 1.
4 VCC Power-Supply Voltage
5 SCK Serial-Clock Input
6CS Active-Low Chip Select. Set CS low to
enable the serial interface.
7 SO Serial-Data Output
8 DNC Do Not Connect
CS
SCKVCC
1
+
2
8
7
DNC
SOT-
T+
GND
SO
TOP VIEW
3
4
6
5
MAX31855
MAX31855
ADC
DIGITAL
CONTROL
COLD-JUNCTION
COMPENSATION
FAULT
DETECTION
REFERENCE
VOLTAGE
S4
S1
S2
S3
S5 SCK
VCC
VCC
SO
CS
GND
T+
T-
MAX31855
Maxim Integrated
7
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Table 1. Thermocouple Wire Connections and Nominal Sensitivities
Detailed Description
The MAX31855 is a sophisticated thermocouple-to-
digital converter with a built-in 14-bit analog-to-digital
converter (ADC). The device also contains cold-junction
compensation sensing and correction, a digital control-
ler, 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 com-
patible 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 equiv-
alent temperature values, it is necessary to compensate
for the difference between the thermocouple cold-
junction side (device ambient temperature) and a 0NC
virtual reference. For a K-type thermocouple, the volt-
age changes by about 41FV/NC, which approximates
the thermocouple characteristic with the following linear
equation:
VOUT = (41.276FV/NC) x (TR - TAMB)
where VOUT is the thermocouple output voltage (FV), TR
is the temperature of the remote thermocouple junction
(NC), and TAMB is the temperature of the device (NC).
Other thermocouple types use a similar straight-line
approximation but with different gain terms. Note that the
MAX31855 assumes a linear relationship between tem-
perature 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
TYPE T- WIRE T+ WIRE TEMP RANGE (°C) SENSITIVITY (µV/°C)
COLD-JUNCTION
SENSITIVITY (µV/°C)
(0NC TO +70NC)
KAlumel Chromel -270 to +1372 41.276
(0NC to +1000NC) 40.73
JConstantan Iron -210 to +1200 57.953
(0NC to +750NC) 52.136
NNisil Nicrosil -270 to + 1300 36.256
(0NC to +1000NC) 27.171
SPlatinum Platinum/Rhodium +50 to +1768 9.587
(0NC to +1000NC) 6.181
TConstantan Copper -270 to +400 52.18
(0NC to +400NC) 41.56
EConstantan Chromel -270 to +1000 76.373
(0NC to +1000NC) 44.123
RPlatinum Platinum/Rhodium -50 to +1768 10.506
(0NC to +1000NC) 6.158
MAX31855
Maxim Integrated
8
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 con-
tinues 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 tem-
perature as the reference junction. It then measures the
voltage from the thermocouple’s output at the reference
junction and converts this to the noncompensated ther-
mocouple temperature value. This value is then added
to the device’s die temperature to calculate the thermo-
couple’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, tCONV, three functions are
performed: the temperature conversion of the internal
cold-junction temperature, the temperature conversion of
the external thermocouple, and the detection of thermo-
couple faults.
When executing the temperature conversion for the inter-
nal cold-junction compensation circuit, the connection to
signal from the external thermocouple is opened (switch
S4) and the connection to the cold-junction compensa-
tion 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 cold-
junction 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.
During fault detection, the connections from the exter-
nal thermocouple and cold-junction compensation cir-
cuit 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 cir-
cuit 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 indi-
cate 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 inter-
faced 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 com-
pensated 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 thermo-
couple 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 uncon-
nected, 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.
MAX31855
Maxim Integrated
9
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Table 3. Memory Map—Descriptions
Table 4. Thermocouple Temperature Data
Format
Table 5. Reference Junction Temperature
Data Format
Note: The practical temperature ranges vary with the
thermocouple type.
Table 2. Memory Map—Bit Weights and Functions
BIT NAME DESCRIPTION
D[31:18] 14-Bit Thermocouple
Temperature Data These bits contain the signed 14-bit thermocouple temperature value. See Table 4.
D17 Reserved This bit always reads 0.
D16 Fault This bit reads at 1 when any of the SCV, SCG, or OC faults are active. Default value
is 0.
D[15:4] 12-Bit Internal Temperature
Data
These bits contain the signed 12-bit value of the reference junction temperature.
See Table 5.
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.
TEMPERATURE
(NC)
DIGITAL OUTPUT
(D[31:18])
+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
TEMPERATURE
(NC)
DIGITAL OUTPUT
(D[15:4])
+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
14-BIT THERMOCOUPLE
TEMPERATURE DATA RES FAULT
BIT
12-BIT INTERNAL TEMPERATURE
DATA RES SCV
BIT
SCG
BIT
OC
BIT
BIT D31 D30 … D18 D17 D16 D15 D14 … D4 D3 D2 D1 D0
VALUE Sign MSB 210
(1024NC) …LSB 2-2
(0.25NC) Reserved 1 =
Fault Sign
MSB
26
(64NC)
…LSB 2-4
(0.0625NC) Reserved
1 =
Short
to
VCC
1 =
Short
to
GND
1 =
Open
Circuit
MAX31855
Maxim Integrated
10
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Applications Information
Noise Considerations
Because of the small signal levels involved, thermocou-
ple temperature measurement is susceptible to power-
supply 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 thermo-
couple 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 measure-
ment 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:
• Usethelargestwirepossiblethatdoesnotshuntheat
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.
• Avoid mechanical stress and vibration, which could
strain the wires.
• When using long thermocouple wires, use a twisted
pair extension wire.
• Avoidsteeptemperaturegradients.
• Trytousethethermocouplewirewellwithinitstem-
perature rating.
• Usethepropersheathingmaterialinhostileenviron-
ments to protect the thermocouple wire.
• Useextensionwireonlyatlowtemperaturesandonly
in regions of small gradients.
• Keepaneventlogandacontinuousrecordofthermo-
couple resistance.
MAX31855
Maxim Integrated
11
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Ordering Information
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.
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.
PART THERMOCOUPLE TYPE MEASURED TEMP RANGE PIN-PACKAGE
MAX31855KASA+ K -200NC to +1350NC8 SO
MAX31855KASA+T K -200NC to +1350NC8 SO
MAX31855JASA+ J -40NC to +750NC8 SO
MAX31855JASA+T J -40NC to +750NC8 SO
MAX31855NASA+ N -200NC to + 1300NC8 SO
MAX31855NASA+T N -200NC to + 1300NC8 SO
MAX31855SASA+ S +50NC to +1600NC8 SO
MAX31855SASA+T S +50NC to +1600NC8 SO
MAX31855TASA+ T -250NC to +400NC8 SO
MAX31855TASA+T T -250NC to +400NC8 SO
MAX31855EASA+ E -40NC to +900NC8 SO
MAX31855EASA+T E -40NC to +900NC8 SO
MAX31855RASA+ R -50NC to +1770NC8 SO
MAX31855RASA+T R -50NC to +1770NC8 SO
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
8 SO S8+4 21-0041 90-0096
MAX31855
12
Cold-Junction Compensated
Thermocouple-to-Digital Converter
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
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
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
3, 8, 9, 11
MAX31855

Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
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 The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.