MAX31855 Evaluation Kit
Evaluates: MAX31855
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
General Description
The MAX31855 evaluation kit (EV kit) provides the
hardware and software (GUI) necessary to evaluate the
MAX31855 cold-junction compensated thermocouple-to-
digital converter.
The MAX31855 EV kit comes with a MAX31855KASA+
soldered to the PCB. This is the K-type thermocouple ver-
sion of the MAX31855. Other thermocouple types can be
evaluated by procuring the desired thermocouple, ther-
mocouple socket, and corresponding MAX31855. Contact
the factory for free samples of the MAX31855 to match
your desired thermocouple type. See the Evaluating Other
Thermocouple Types section for part numbers and addi-
tional information regarding other thermocouple types.
EV Kit Contents
S Assembled Circuit Board Including MAX31855KASA+
S Mini-USB Cable
S K-Type Thermocouple
Features
S Includes Everything Needed to Evaluate a K-Type
Thermocouple
S EV Kit Hardware is USB Powered (USB Cable Included)
S Windows XP®, Windows Vista®, and Windows® 7
Operating Systems-Compatible Software
S USB HID Interface
S Graphical User Interface (GUI) Consists of a
Single .EXE File
S Second Channel Allows Easy Evaluation of Other
Thermocouple Types
S RoHS Compliant
MAX31855 EV Kit Files
Ordering Information appears at end of data sheet. MAX31855 EV Kit Board
19-6072; Rev 0; 10/11
Note: The .EXE file is downloaded as a .ZIP file.
Windows XP, Windows Vista, and Windows are registered trademarks of Microsoft Corp.
FILE DESCRIPTION
MAX31855EVkit.EXE Application program
MAX31855 Evaluation Kit
Evaluates: MAX31855
2Maxim Integrated
Quick Start
Note: In the following sections, software-related items
are identified by bolding. Text in bold refers to items
directly from the EV kit software. Text in bold and under-
lined refers to items from the Windows operating system.
Required Equipment
• PC with Windows XP, Windows Vista, or Windows 7
OS with a spare USB port
• K-typethermocouple(included)
• Mini-USBcable(included)
• EVkithardware
Procedure
Follow the steps below to get started measuring tem-
perature using the MAX31855 interfaced to a K-type
thermocouple.
1) Connect the included K-type thermocouple to J2
(thermocouple socket) of the EV kit hardware. One
terminal of the thermocouple is wider than the other,
ensuring proper polarity.
2) Ensure that jumper/shunt J4 is installed and is select-
ing Channel 1.
3) Set the EV kit hardware on a nonconductive surface
that ensures nothing on the PCB gets shorted togeth-
er.
4) Prior to starting the GUI, connect the EV kit hardware
to a PC using the supplied mini-USB cable, or equiva-
lent. The COM LED (D2) should flash between red
and orange.
5) Windows should automatically begin installing the
necessary device driver. The USB interface of the
EV kit hardware is configured as an HID device and
therefore does not require a unique/custom device
driver. Once the driver installation is complete, a
Windows message appears near the System Icon
menu indicating that the hardware is ready to use. Do
not attempt to run the GUI prior to this message. If you
do, you must close the application and restart it once
the driver installation is complete. On some versions
of Windows, Administrator privileges may be required
to install the USB device.
6) Go to www.maximintegrated.com/MAX31855EVKIT
to download the latest version of the EV kit software,
titled MAX31855EVkit.ZIP. Save the EV kit software to a
temporary folder.
7) Open the .ZIP file and extract the .EXE file to your
desired location. The .EXE file is the actual EV kit GUI
and not an install program. You can store the .EXE
wherever you like and then uninstall it later by simply
deleting the .EXE file.
8) Once the device driver installation is complete (from
an earlier step), double-click the .EXE file to run the
GUI. A message box stating The publisher could
not be verified. Are you sure you want to run this
software? may appear. If so, click Run.
9) When the GUI appears, the EV Kit Status group box
should indicate that the EV kit hardware is ready. Also,
the COM LED (D2) should turn green.
10)Click the Single Read button to read the temperature.
A valid temperature should be displayed along with all
four Alarm Status indicators remaining green. At this
point, the EV kit and setup is fully functional and ready
to begin evaluating the MAX31855. If any issues arise,
see the Troubleshooting section.
Detailed Description of Software
Figure 1 shows a screenshot of the MAX31855 GUI.
EV Kit Status Section
On the right-hand side of the GUI is a section titled EV
Kit Status. It is used to indicate the status of the com-
munication between the GUI and the EV kit hardware. If
everything is working properly, a message indicates that
the hardware is present and/or ready. Otherwise, EV Kit
not found. is displayed.
Thermocouple Type Section
The drop-down box in this section is used to select the
thermocouple type installed on the EV kit hardware. See
Table 1 for the list of possible settings. Out-of-the-box,
the hardware contains a K-type version of the MAX31855
along with a K-type thermocouple and socket. Therefore,
the drop-down box defaults to the K-type setting. The
thermocouple type selection is used by the GUI to calcu-
late the linearized temperature values.
Table 1. Thermocouple Types and
Sensitivities
*Default setting.
TYPE SENSITIVITY (µV/NC)
K* 41.276
J57.953
N 36.256
S9.587
T 52.18
E76.373
R 10.506
MAX31855 Evaluation Kit
Evaluates: MAX31855
3Maxim Integrated
Read from the MAX31855 Section
Interfacing to the MAX31855 is simple. The interface
is read-only and consists of one 32-bit shift register.
When the Single Read button is pressed, all 32 bits
are read, parsed, and then displayed. The raw data
read from the device is shown in both binary and hexa-
decimal format in the edit boxes labeled Raw B[31:0].
Furthermore, the four fault bits are analyzed and then
their states are indicated in the Alarm Status sec-
tion. The Raw Thermocouple Temperature and Cold
Junction Temperature edit boxes are calculated. And
finally, the Linearized Thermocouple Temperature edit
box is calculated using the sensitivity value and NIST
coefficients to compensate for thermocouple nonlineari-
ties. Refer to the MAX31855 IC data sheet for additional
information.
Multiple Reads Section
This section allows the user to enter a desired number
of samples (temperature readings) as well as the delay
between the samples (in milliseconds) in order to auto-
mate temperature readings. It is also possible to write the
results to a file by clicking the Log to file checkbox and
providing a folder and filename for the comma separated
value (.CSV) file to be stored.
Figure 1. MAX31855 EV Kit GUI
MAX31855 Evaluation Kit
Evaluates: MAX31855
4Maxim Integrated
Detailed Description of Hardware
The MAX31855 EV kit hardware provides everything
needed to evaluate a K-type thermocouple. In addition to
a thermocouple and MAX31855, the hardware includes
a USB interface that is used to communicate with the
PC-based software. An added feature is that the hard-
ware is USB powered, meaning that no power supplies
are needed.
Thermocouple Channels
The EV kit hardware features two thermocouple channels.
Channel 1 comes preconfigured with a MAX31855KASA+,
K-type thermocouple, and thermocouple socket. A sec-
ond channel is provided to make it easy to evaluate other
thermocouple types. Channel 2 is almost fully populated,
missing only the desired MAX31855 version, correspond-
ing thermocouple, and thermocouple socket. A jumper
(J4) is used to select the desired channel. The following
section describes how to modify the hardware in order to
evaluate other thermocouple types.
Evaluating Other Thermocouple Types
To use Channel 2, see Table 2 for the part numbers of the
three items required for the desired thermocouple type.
Once the three items have been procured, carefully
solder the Maxim device to the footprint labeled U3 and
the thermocouple socket to the footprint labeled J3.
Obviously, make sure this is done with the board unpow-
ered. Move the jumper, J4, to the Channel 2 position.
Finally, connect the thermocouple to the socket.
Reconnect the USB cable to the PC and then run the
GUI. Select the correct Thermocouple Type from the
drop-down box. The hardware and software are now
ready to begin evaluation.
Description of Channel Selection Jumper
The jumper, J4, is used to select the desired channel.
See Table 3 for additional details.
Table 2. Items Required to Evaluate Other Thermocouple Types
Table 3. MAX31855 EV Kit Jumper Description (J4)
*Thermocouple and socket part numbers are Omega part numbers (www.omega.com). Contact Omega for RoHS part numbers.
*Default position.
TYPE MAXIM PART THERMOCOUPLE* SOCKET*
K MAX31855KASA+ 5SRTC-GG-K-24-36 PCC-SMP-K-5
J MAX31855JASA+ 5SRTC-GG-J-24-36 PCC-SMP-J-5
N MAX31855NASA+ NMQIN-010E-6 (unverified) PCC-SMP-N-5
S MAX31855SASA+ — —
T MAX31855TASA+ 5SRTC-GG-T-24-36 PCC-SMP-T-5
E MAX31855EASA+ 5SRTC-GG-E-24-36 PCC-SMP-E-5
R MAX31855RASA+ — —
JUMPER JUMPER POSITION DESCRIPTION
J4
1-2* Selects Channel 1. The SO (serial out) pin of the Channel 1 MAX31855 is connected to
the USB PC Interface
2-3 Selects Channel 2. The SO (serial out) pin of the Channel 2 MAX31855 is connected to
the USB PC Interface
MAX31855 Evaluation Kit
Evaluates: MAX31855
5Maxim Integrated
Troubleshooting
All effort was made to ensure that each EV kit works on the first try directly out of the box. In the rare occasion that a
problem is suspected, see the table below to help troubleshoot the issue.
SYMPTOM CHECK SOLUTION
GUI says hardware not found.
Is the LED labeled D1 on?
Ifyes,thentheelectronicfuse,U7,isinafaultstate.
Inspect for electrical shorts on the PCB and make sure
that the PCB is not sitting on a conductive surface.
Does the LED labeled D2 turn
green when the GUI is running?
If not, then exit the GUI and try running it again. If D2
still does not turn green, then exit the GUI and try con-
necting the USB cable to a different USB port on the
PC and wait for a Windows message that states the
hardware is ready to use. Run the GUI again.
Are any of the LEDs illuminated? If not, then the PCB may not be getting power from
USB. Try a different USB cable or a different USB port.
GUI appears to work, but the raw
data is all zeros. Jumper (J4) Make sure jumper, J4, is installed and connected to the
correct channel.
The “Fault” and “Open Circuit”
indicators are red in the Alarm
Status section of the GUI.
Is the thermocouple connected? Verify that the thermocouple is connected (to the cor-
rect channel).
MAX31855 Evaluation Kit
Evaluates: MAX31855
6Maxim Integrated
Figure 2. MAX31855 EV Kit Schematic (Sheet 1 of 2)
1
2
3
J4
SO Jumper
GND
1
T-
2
T+
3
Vcc
4SCK5
CS 6
SO 7
NC 8
U1
MAX31855
in11
in22
GND
3
U4
NUP2105
in11
in22
GND
3
U2
NUP2105
C2
0.01uF
C3
DNP
C4
DNP
C6
0.01uF
C7
DNP
C8
DNP
C5
0.1uF
C1
0.1uF
1 2
0603
L2
BLM18PG471
1 2
0603
L1
BLM18PG471
1 2
0603
L3
BLM18PG471
1 2
0603
L4
BLM18PG471
GND
1
T-
2
T+
3
Vcc
4SCK5
CS 6
SO 7
NC 8
MAX31855
U3
DNP
GND
GND GND
GND
GND
GND GND
GND
GND
GND
PCB Layout Notes
1. MAX31855 should be as close as possible to the thermocouple connector.
2. Use as much copper as possible between MAX31855 and connector (PCC-SMP-x-x).
3. Place decoupling CAP close to their voltage supply.
4. Use a large ground plane to improve the device’s temperature measurement accuracy.
3V3
3V3
TP11
DNP
TP12
DNP
TP3
CS_BAR
TP2
SCK
TP1
SO
TP4TP5TP6TP7
TP9
TP10
GND
3V3
SO
Jum
pe
m
m
r
in
1
1
2
2
G
N
D
3
U
4
NU
P
2
1
05
C
6
0.01u
F
C
7
D
N
P
C
8
DN
P
C
5
0
.
1
u
F
1
2
0603
L
3
B
L
M
18
P
G
4
7
1
1
2
0603
L
4
B
L
M1
8
P
G
4
7
1
G
N
D
D
D
1
T
-
2
T
+
3
Vc
c
c
c
4
SC
K
5
C
S
6
S
O
7
N
C
8
MAX
3
1
85
5
U
3
DN
P
GN
D
G
N
D
G
N
D
GN
D
G
N
D
3
V
3
T
P
12
DN
P
NOTE: Second circuit
available for customer to
add another type of
thermocouple
DNP U3 and J3.
NOTE: All R, C and L footprints are 0805 unless otherwise stated.
+
-
PCC-SMP-x-x
J3
+
-
J2
PCC-SMP-K-5-ROHS
NOTE: U1 and J2 will be
populated with K type
thermocouple.
TP8
SO
SCK
CS
MAX31855 Evaluation Kit
Evaluates: MAX31855
7Maxim Integrated
Figure 3. MAX31855 EV Kit Schematic (Sheet 2 of 2)
MCLR
1
P3 HB
2
COM_LED/BOOT
3
P1
4
P2
5
RCV
6
P6/CS
7
GND
8
OCS1
9
OSC2
10
P4
11
UOE
12
PS_VAR
13
Vusb
14 D-/VM15
D+/VP16
ENUM 17
P9/SDO 18
GND 19
VDD 20
P11/SDA/SDI 21
P10/SCL/SCK22
VMO 23
VPO24
USB_DET 25
P5 26
P7/1W_DQ 27
P8/1W_PU 28
MC
L
R
P
3
H
B
CO
M
_
L
ED/BOO
T
P
1
P
2
RC
V
P
6
/
C
S
GN
D
OCS
1
OSC
2
P
4
UO
E
P
S
_
VA
R
V
us
b
D
-
/
V
M
D
+
/V
P
EN
U
M
P
9/
SD
O
GN
D
VD
D
P
1
1/SDA/SD
I
P
10
/
SC
L
/
SC
K
VM
O
V
P
O
US
B
_D
E
T
P
5
P7
/
1W
_
D
Q
P
8
/1
W
_
P
U
SOIC 28-pin
U5
PIC18LF2550
Vbus 1
D- 2
D+ 3
I.D. 4
GND5
J1
USB_5PIN
OUT 1
GND 2
FLAG 3
ON
4
IN
5
MAX4787EXK+TCT-ND
SC70-5
U7
24.9
R1
24.9
R2
24.9
R3
SO
SCK
CS
0
R13
0
R14
0
R15 0.1uF
C9
0.1uF
C10
330
R16 1206
D1
Fault LED
GND
GND GND
D+
D-
D-
D+
330
R6
1M
R10
4.7K
R8
22pF
C15
22pF
C16
20MHz
CRYSTAL_SM
X1
GND
GND
GND
VBUS
SHDN
1
GND
2
IN
3OUT4
BP 5
SOT23-5
U6
MAX8868EUK33-T
1uF
C11
1uF
C12
0.01uF
C13
GND GND
5VDD
3V3
3V3
3V3
N
OTE: All R, C and L footprints are 0805 unless
otherwise stated.
4.7K
R4
DNP
R5
DNP
C14
GND
3V3
BOOTLOAD
3-Wire interface (Read Only)
PCB notes:
D1, D2, R5 and R9 must be on top layer.
R9 DNP
GND
Reset
1uF
C17
GND
4.7K
R12
3V3
Select Fixed Voltage
GND
1
LED_BI-COLOR
D2
330
R7
RED
GREEN
1
D
2
R
E
D
G
R
E
E
N
D
N
1.0uF
C18
0.1uF
C19
0
R11
MAX31855 Evaluation Kit
Evaluates: MAX31855
8Maxim Integrated
Figure 4. MAX31855 EV Kit PCB Layout—Top
Figure 5. MAX31855 EV Kit PCB Layout—Bottom
MAX31855 Evaluation Kit
Evaluates: MAX31855
9Maxim Integrated
Note: Indicate that you are using the MAX31855 when contacting these component suppliers.
Component List
Component Suppliers
DESIGNATION QTY DESCRIPTION
C1, C5, C9,
C10, C19 5
0.1FFX7Rceramiccapacitors
(0805)
VenkelC0805X7R160-104KNE
C2, C6, C13 3
0.01FFX7Rceramiccapacitors
(0805)
VenkelC0805X7R250-103KNE
C3,C4,C7,C8,
C14 0Do not populate (0805)
C11,C12,C17,
C18 4
1FFX7Rceramiccapacitors
(0805)
VenkelC0805X7R250-105KNE
C15, C16 222pF ceramic capacitors (0805)
Venkel C0805COG101-220KNP
D1 1 Red LED (1206)
Kingbright APT3216SURCK
D2 1 Red/green dual LED
Kingbright BM2012SURKCGKC
J1 1 5-pin, female Mini-USB
54819-0519
J2 1 K-type thermocouple socket
Omega PCC-SMP-K-5-ROHS
J3 0 Thermocouple socket
Do not populate
J4 1 1 x 2 header, 2.54mm pitch
22-28-4360
L1-L4 4470I ferrite beads (0603)
BLM18PG471SN1D
R1, R2, R3 324.9I Q1% resistors (0805)
Venkel CR0805-10W-24R9FT
R4, R8, R12 34.7kI Q1% resistors (0805)
VenkelCR0805-10W-4701FT
R6,R7,R16 3330I Q1% resistors (0805)
Venkel CR0805-10W-3300FT
DESIGNATION QTY DESCRIPTION
R10 1 1MI Q1% resistor (0805)
Venkel CR0805-10W-1004FT
R11, R13, R14,
R15 40I Q1% resistor (0805)
Venkel CR0805-10W-000FT
R5, R9 0Do not populate (0805)
TP1, TP2, TP3 3White test points
Keystone 5012
TP4-TP8 5Black test points
Keystone 5011
TP9, TP10 2Red test points
Keystone 5010
TP11, TP12 —Do not populate
U1 1
Thermocouple-to-digital
converter (8 SO)
Maxim MAX31855KASA+
U2, U4 2TVS diode (SOT-3)
NUP2105TL1G
U3 0 MAX31855
Do not populate
U5 1 PIC18LF2550-I/SO (28 SO)
U6 1 Linear regulator (5 SOT23)
Maxim MAX8868EUK33+
U7 1Current-limitswitch(5SC70)
MaximMAX4787EXK+
X1 1 20MHz, 20pF SMT crystal
403I35E20M00000
— 1 Jumper/shunt
— 1 Mini-USB cable
— 1 K-type thermocouple
Omega 5SRTC-GG-K-24-36-ROHS
— 1 PCB: MAX31855 EV Kit
SUPPLIER PHONE WEBSITE
Omega Engineering, Inc. 888-826-6342 www.omega.com
Venkel Ltd. 800-950-8365 www.venkel.com
MAX31855 Evaluation Kit
Evaluates: MAX31855
10Maxim Integrated
#Denotes a RoHS-compliant device that may include lead that
is exempt under the RoHS requirements.
Ordering Information
PART TYPE
MAX31855EVKIT# EV Kit
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 11
© 2011 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX31855 Evaluation Kit
Evaluates: MAX31855
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 10/11 Initial release —
MAX31855 Evaluation Kit
Evaluates: MAX31855
12Maxim Integrated
Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Maxim Integrated:
MAX31855EVKIT#