MAX31865 Evaluation Kit Evaluates: MAX31865
General Description
The MAX31865 evaluation kit (EV kit) provides the hard-
ware and software (graphical user interface) necessary
to evaluate the MAX31865 RTD-to-digital Converter. The
EV kit includes a MAX31865ATP+ installed as well as a
USB-to-SPI interface.
The USB-to-SPI master section of the EV kit can be used
to interact with the MAX31865 EV kit software and exer-
cise the device’s functionality.
EV Kit Contents
● AssembledcircuitboardincludingMAX31865ATP+
and USB-to-SPI circuitry
● Mini-USBcable
● Two0.2injumperwires
● 1kΩresistor
Features
● EasyEvaluationoftheMAX31865
● FullyAssembledandTested
● USBHIDInterface
● EVKitHardwareisUSBPowered(USBCable
Included)
● WindowsXP®-,WindowsVista®-, and
Windows® 7-Compatible Software
● RoHSCompliant
● ProvenPCBLayout
MAX31865 EV Kit Files
EV Kit Photo
Note: The .EXE file is downloaded as a .ZIP file.
19-6500; Rev 0; 11/12
Ordering Information appears at end of data sheet.
Windows, Windows XP, and Windows Vista are registered
trademarks and registered service marks of Microsoft
Corporation.
FILE DESCRIPTION
MAX31865EVKitSoftwareInstall.EXE Application program
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Component List
*Exposed pad.
DESIGNATION QTY DESCRIPTION
C2,C5,C10,
C212 40.1µFX7Rceramiccapacitors(0805)
TDKC2012X7R1H104K
C4,C215 2 Ceramiccapacitors(0805),donot
populate
C201,C202,
C204 310µFX7Rceramiccapacitors(0805)
TDKC2012X7R1A106K
C203,C214 2 10nFceramiccapacitors(0805)
TDKC2012C0G1H103J
C211 11.0µFceramiccapacitor(0805)
TDKC2012X7R1H105K
C213 1220nFceramiccapacitor(0805)
TDKC2012X7R1H224K
CON4 1
4-positionscrewterminal,2.54mm
pitch
PhoenixContact1725672
D1 1 RedLED(1206)
KingbrightAPTR3216EC
D20,D21 2 Red/greendualLEDs
KingbrightAPHBM2012SURKCGKC
D22 1Schottky diode
ROHMSemiRB060M-30TR
J20 15-pin mini USB, female
Molex54819-0519
J21 12-pinheader,donotpopulate
R1 1 Resistor(0805),donotpopulate
R2 2 Resistor(1206),donotpopulate
R3 1
4kΩ±0.1%resistor(1/8W,through
hole)
VishayPTF564K0000BYEB
R4 1 1.2kΩ±1%resistor(0805)
VishayCRCW08051K20FKEA
R5–R10,R201,
R202,R214 90Ω±1%resistors(0805)
VishayCRCW08050000Z0EA
R11 110MΩ±1%resistor(0805)
Vishay CRCW251210M0FKEG
R203,R205 2 560Ω±1%resistors(0805)
VishayCRCW0805560RFKEA
R204 156kΩ±1%resistor(0805)
VishayCRCW0805056KFKTA
DESIGNATION QTY DESCRIPTION
R206 145.3kΩ±1%resistor(0805)
VishayCRCW080545K3FKEA
R207 110kΩ±1%resistor(0805)
VishayCRCW0805010KFKTA
R210 14.7kΩ±1%resistor(0805)
VishayCRCW08054K70FKEA
R211,R212 2 330kΩ±1%resistors(0805)
VishayCRCW0805330KFKTA
R213 12.2kΩ±1%resistor(0805)
VishayCRCW08052K20FKEA
TP1,TP10 2 Red test points
Keystone5010
TP2–TP6 5Whitetestpoints
Keystone5012
TP7, TP9,
TP11 3Black test points
Keystone5011
U1 1
RTD-to-digital converter
(20TQFN-EP*)
Maxim MAX31865ATP+
U20 1Microcontroller(28SO)
MicrochipPIC18LF2550-I/SO
U21 1
50mAto600mAcurrent-limitswitch
(6SOT23)
Maxim MAX4995AAUT+
U22 1500mALDOregulator(8TDFN-EP*)
MaximMAX8902BATA+
X1 1 48MHz,3.3Voscillator(SMD)
AVXKC3225A48.0000C30E00
—2 0.2injumperwires
— 1 1.0kΩ±1%resistor(0805)
VishayCRCW08051K00FKEA
— 1 Mini-USB cable
— 1 PCB: MAX31865 EV kit
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Quick Start
Note: In the following sections, software-related items are
identified by bolding. Text in bold refers to items directly
from the install or EV kit software. Text in bold and under-
linedreferstoitemsfromtheWindowsoperatingsystem.
Required Equipment
● WindowsXP,WindowsVista,orWindows7PC
● USBport
● Mini-USBcable(included)
● EVkithardware(included)
● Micro screwdriver, bladed, size 0.4mm x 2.0mm x
60mm
● Jumperwireandaresistor(included)oranRTD(NOT
included)
Procedure
TheEVkitisfullyassembledandtested.Followthesteps
below to verify board operation:
1) Verify the two jumper wires (included) are properly
secured in the terminal block in accordance with the
2-wireRTDSensorConnectordiagramonthePCB’s
silkscreen(Figure6).
2) Verify the 1kΩ resistor is properly secured in the
terminal block connecting the RTDIN+ terminal to the
RTDIN- terminal.
3) Set the EV kit hardware on a nonconductive surface
that ensures that nothing on the PCB gets shorted to
the workspace.
4) PriortostartingtheGUI,connecttheEVkithardware
to a PC using the supplied mini-USB cable, or equiva-
lent. The POWER LED (D20) should be green and
theCOMLED(D21)shouldberedandslowlyflash
orange.
5) Windows should automatically begin installing the
necessary device driver. The USB interface of the
EVkithardware is configured as a 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trytoruntheGUIpriortothismessage,close
the application and restart it once the driver instal-
lation is complete. On some versions of Windows,
administrator privileges may be required to install the
USB device.
6) Once the device driver installation is complete,
visit www.maximintegrated.com/MAX31865evkit to
download the latest version of the EV kit software,
MAX31865EVKitSoftwareInstall.ZIP.SavetheEVkit
software to a temporary folder.
7) Openthe.ZIPfileanddoubleclickthe.EXEfiletorun
the installer. A message box stating “The publisher
could not be verified. Are you sure you want to run this
software?” may appear. If so, click Yes.
8) The installer GUI appears. Click Next and then
Install. Once complete, click Close.
9) Go to Start >> All Programs. Look for the
MAX31865EVKitSoftware folder and click on
MAX31865EVKitSoftware.EXEinsidethefolder.
10)When the GUI appears, the text below the Maxim
Integrated logo should indicate that the EV kit hard-
wareisconnected.TheCOMLED(D21)turnsoffand
flashes red when communication occurs.
Component Suppliers
Note: Indicate that you are using the MAX31865 when contacting these component suppliers.
SUPPLIER PHONE WEBSITE
AVX Corporation 843-946-0238 www.avx.com
Keystone Electronics Corp. 209-796-2032 www.keyelco.com
Kingbright Corporation 909-468-0500 www.kingbrightusa.com
Molex 800-786-6539 www.molex.com
Phoenix Contact 800-808-7177 www.phoenixcontact.com
ROHM Co., Ltd. 858-625-3630 www.rohm.com
TDK Corp. 847-803-6100 www.component.tdk.com
Vishay 402-563-6866 www.vishay.com
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Figure 1. MAX31865 EV Kit GUI (Registers Tab)
Detailed Description of Software
Device Conguration
Upon successful completion of the setup procedure, the
user is ready to begin evaluation of the device. The device
powers up in “normally off” conversion mode. To begin
conversions, first enable the VBIAS output by clicking
the On radio button located in the MAX31865 Setup Info
group box in the Registerstab(Figure1).Next,enable
conversions by changing the Conversion Mode to Auto
by clicking the Auto radio button. It is now time to read the
results. This is accomplished by clicking the Read button
in the RTD Resistance Register group box. The conver-
sion results are displayed below the button in hex and
binary format. Also note that the ADC result is displayed
in decimal format. The RTD resistance is then calculated
from the ADC result and the value entered in the RREF
Nominal Resistance edit box located in the MAX31865
Setup Infogroupbox.Withthesupplied1kΩresistor,the
calculatedRTDresistanceshouldbe1kΩ±6%duetothe
tolerance of the provided resistors. Note: Since there is
not an RTD connected at this time, the RTD temperature
equations are not valid registers.
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Figure 2. MAX31865 EV Kit GUI (Graphing/Data Tab)
Reads
Each register of the device can be read from the
Registers tab of the GUI. Clicking a read button does
a single read of the register and updates the associated
data fields. There is also an option to do continuous reads
of the device. This Polling feature is located in the top
rightsectionoftheGUI.Tostartpolling,selectthedelay
between reads: 150ms, 300ms, 500ms, or 1000ms and
click Start. Each poll reads all eight registers of the device
and updates their associated data fields on the Registers
tab and collects data for the Graphing/Data tab. Once the
continuous read starts, the button text changes to Stop
for the user to stop the reads.
Writes
WritestothedeviceareaccomplishedfromtheRegisters
tab. Clicking on any of the radio buttons in the MAX31865
Setup Info group box automatically writes that bit to
the configuration register, followed by a read to update
the associated data fields. The high- and low-threshold
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registers can be set in the Fault Status group box with
the associated input boxes and Write buttons. This data
is input in hexadecimal format only. The master-initiated
fault-detection cycle can be run from the Fault Status
group box by selecting the corresponding button. Note
that if using the Manual Timing Mode that once Step 1
has been selected it must be followed by selecting Step 2.
Graphing
This GUI comes complete with a very simple graphing
tool located in the Graphing/Data tab (Figure 2). The
Graphing/Data tab plots the polled values in a graph.
Polled values are collected any time the Polling feature
is active. Three data options can be displayed; the
calculated Resistance Value, the temperature calculated
using the Simple Linearizing Method, or the temperature
calculated using Callendar-Van Dusen Equation with
IEC 751 coefficients and the user-supplied RTD nominal
0°Cresistance.The Simple Linearizing Method is the
straight-line approximation, as defined by the equation
shown on the Registers tab in the RTD Resistance
Register group box. Click the desired checkbox to plot
thecollecteddata.Thegraphdisplaysthelatest10,000
polledvaluesandwhenthepolledcountreaches10,000,
the graph deletes the oldest polled values and adds a new
polled value. To reset and clear all collected data, select
the Clear Graph button. To save all the data graphed to a
comma-separated value (.CSV) file, press the Save Data
button and provide a folder and filename.
Figure 3. MAX31865 Data Table
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Detailed Description of Hardware
User-Supplied SPI Interface
The USB-to-SPI master section of the EV kit is not nec-
essary for the proper operation of the device. If the user
wants to supply the SPI interface, the USB-to-SPI master
section of the EV kit can be disconnected by removing
resistorsR7–R10.ConnecttestpointsSDO,CS,SCLK,
SDI,andGND.TheDRDY output signal from the device
can also be routed to a different master by removing
resistor R6 and connecting to the DRDYandGND test
points.
User-Supplied Power Supply
To disconnect the device from the USB-powered supply
and apply an outside power source, remove resistor R5
andconnecttothe3.3VandGNDtestpoints.
User-Supplied RTD
The EV kit comes with a 1kΩ resistor and two jumper
wires installed to the CON4 terminal block. This is
to allow for an out-of-the-box functioning system, but
does not provide real-world temperatures. To evaluate
temperature, an RTD must be connected. Connect a
PT1000 RTD to make the RTD temperature Simple
Linearizing equation and the RTD temperature
Calendar-Van Duesen Equation in the RTD Resistance
Register group box valid. To connect a user-supplied
RTD, loosen the terminal block with a screwdriver and
removethepreinstalledresistorandjumperwires.Insert
theRTDandtightentheterminals.Notethatfora2-wire
RTD, the two jumper wires also need to be inserted in
accordancewiththe2-wireRTDSensorConnectordia-
gram on the PCB’s silkscreen. Also, for a 3-wire RTD, one
jumperwireneedstobeinsertedinaccordancewiththe
3-wire RTD Sensor Connector diagram on the PCB’s silk-
screen.The4-wireRTDdoesnotneedanyjumperwires.
User-Supplied Reference Resistor
The EV kit comes equipped with a 4kΩ, 10ppm/°C
temperature coefficient, ±0.1% tolerance reference
resistor. User-supplied reference resistors can also be
used by removing R3 and populating one of the following:
R1(0805footprint),R2(1206footprint),orR3(0.3inaxial
footprint). Properly clean the PCB after any soldering
rework.
Table 1. Hardware Configurations
Table 2. Description of LEDs
HARDWARE ACTION COMPONENTS DESCRIPTION
Connect User-Supplied
Reference Resistor R3 Remove factory-installed reference resistor R3 and populate R1–R3 with
user-supplied reference.
Connect User-Supplied RTD CON4 Removefactory-installedresistorandjumpersfromtheterminalblock
CON4 and insert user-supplied RTD.
Connect DRDY Pin to User-
Supplied Input R6 Remove resistor R6 and connect to the DRDY test point.
Connect User-Supplied Power
Supply R5 RemoveresistorR5andconnecttheusersupplytothe3.3VandGNDtest
points.
Connect User-Supplied SPI
Interface R7–R10 RemoveresistorsR7–R10andconnecttheuserSPIinterfacetotest
points.
LED COLOR DESCRIPTION
D1 Red DRDY:LEDconnectedtotheactive-low/DRDYdata-readyoutput.TheLEDisredwhena
new conversion result is available in the RTD Data registers.
D20(POWER) Red USB Power Fault: A fault occurred due to overvoltage limit, current limit, or thermal limit.
Green USB Power: USB power supply is on.
D21(COM)
Red Communication:Afterthesoftwarehasinitializedthehardware,theLEDashesredwhen
a command from the PC is received.
Off Initialized:Hardwarehasbeeninitializedbysoftware.
Red and
FlashingOrange Waiting:Hardwareispoweredonandwaitingforthesoftwaretobeopened.
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Troubleshooting
All efforts were made to ensure that each kit works on the first try, right out of the box. In the rare occasion that a problem
is suspected, refer to the table below to help troubleshoot the issue.
SYMPTOM CHECK SOLUTION
GUIsayshardwarenot
found.
IstheD20LEDred?
Ifyes,thentheelectronicfuse(U20)isinafaultstate.Inspect
for electrical shorts on the PCB and ensure that the PCB is not
sitting on a conductive surface.
DoestheD21LEDturnoffwhen
theGUIisrunning?
Ifnot,thenexittheGUIandtryrunningitagain.IfD21still
doesnotturnoff,thenexittheGUIandtryconnecting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.IfD21stilldoesnotturnoff,unplugtheUSBcableand
rebootthePC.ConnecttheUSBcableandopentheGUI.
AreanyoftheLEDsilluminated? If not, then the PCB may not be getting power from the USB.
Try a different USB cable or a different USB port.
RTD Data register
reportsall00sorallFFs
Are all terminal block connections
secure and making good contact?
Unscrew all terminals in the terminal block. Remove and reinsert
the RTD resistor, paying special attention to the connector
diagramonthePCBsilkscreenandjumperwires.
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Figure 4. MAX31865 EV Kit Schematic (Sheet 1 of 2)
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10 11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
EP 21
U1
MAX31865 - DUT
FORCE+
FORCE2
RTDIN+
RTDIN-
FORCE-
GND2
GND
SDO
GND1
NC
GND
C4
DNP
C2
0.1uF
GND
3V3TP1
3.3V
C5
0.1uF
GND
R6 0
R7 0
R8 0
R9 0
R100
TP2
DRDY
R4
1.2k
D1
RedLED
3V3
TP3
SDO
TP4
CS
TP5
SCLK
TP6
SDI
TP9
GND
TP7
GND
R34k
R1DNP
R2DNP
Reference Resistor (RREF)
FORCE+
FORCE2
RTDIN+
RTDIN-
FORCE-
RTD Interface (2,3,4-Wire Selectable)
IFORCE+
IFORCE-
VSENSE-
VSENSE+
C10
0.1uF
--------> RTD <-------
PCB Layout Notes:
1. Place MAX31865 close to RTD terminal strip to minimize errors due to trace resistance
2. Use thick traces (more copper) for all 4 traces to RTD terminal strip
3. Balance trace lengths for all 4 traces to RTD terminal strip
4. Decoupling cap close to pin
SD0_MASTER
CS#_MASTER
SCLK_MASTER
SDI_MASTER
DRDY#_MASTER
To SPI Master
Reference Resistor Note:
Populate one RRef Footprint
(0805,1206, through Hole) footprints
available.
Use a high accuracy low drift
component
MOSI
MISO
GND
VDD
DVDD
RTD Interface Notes:
For 2-wire configuration use an external wire to short IFORCE+ to VSENSE+ at the
terminal strip
For 2- and 3-wire configuration use an external wire to short VSENSE- to IFORCE-
at the terminal strip
DGND
CS#
SCLK
SDI
BIAS
REFIN+
REFIN-
ISENSOR
DRDY#
3.3V_MASTER
R5 0
2
3
4
1
RTD Connect
CON4
R11
10M
RTDIN+
Maxim Integrated
│
10
MAX31865 Evaluation Kit Evaluates: MAX31865
www.maximintegrated.com
Figure 5. MAX31865 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
OSC1
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,SDI,SDA 21
P10,SCK,SCL 22
VMO 23
VPO24
USB_DET25
P5 26
P7,1W_DQ27
P8,1W_PU28
U20
PICfor DS3900
Vbus 1
D- 2
D+ 3
I.D. 4
GND 5
J20
USB_5PIN
R203 560
R2010
R2020
R211
330
R212
330
R213
2.2K
R214 0
C204
10uF
C212
0.1uF
C211
1.0uF
C202
10uF
C201
10uF
C213
220nF
C214 10nF
D-
D+
VBUS
5V
3.3V_MASTER
12
D22
3.3V_MASTER
3.3V_MASTER
D+
D-
TP10
3.3V_MASTER
R210
4.7K
C215
DNP
1
2
J21
DNP
VPP
OSC1
HB
COM
Green
D21B
Red
D21A
COM
INH
1
GND
2OUT 3
VCC4
I
N
I
I
H
GN
D
O
U
T
V
C
C
X1
OSC_CMOS_4pin
3.3V_MASTER
CLK
3.3V_MASTER
R204 56k
Red
D20A
Green
D20B
R205
560
C203 10nF
R207
10k
R206
45k
OUT1
GND 2
SETI 3
ON
4IN
5FLAG
6
OU
T
GN
D
S
E
T
I
O
N
I
N
I
I
F
L
A
G
U21
MAX4995A
EP 9
IN
1
GND
2
EN
3
GS
4POK5
FB 6
BYP7
OUT8
I
N
I
I
GN
D
E
N
G
S
P
O
K
F
B
B
Y
P
OU
T
E
P
U22
MAX8902B
USB-to-SPI Master
SCLK_MASTER
SDI_MASTER
SD0_MASTER
CS#_MASTER
DRDY#_MASTER
MISO
MOSI
SCLK
MISO
MOSI
CS#
GND
GND
GND
GND
GND
TP11GND
GND
Maxim Integrated
│
11
MAX31865 Evaluation Kit Evaluates: MAX31865
www.maximintegrated.com
Figure 6. MAX31865 EV Kit PCB Layout—Top
Figure 7. MAX31865 EV Kit PCB Layout—Bottom
Maxim Integrated
│
12
MAX31865 Evaluation Kit Evaluates: MAX31865
www.maximintegrated.com
#Denotes an RoHS-compliant device that may include lead(Pb)
that is exempt under the RoHS requirements.
Ordering Information
PART TYPE
MAX31865EVKIT# 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 specications without notice at any time.
MAX31865 Evaluation Kit Evaluates: MAX31865
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2012Maxim Integrated Products, Inc.
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13
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 11/12 Initial release —
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.
Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
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MAX31865EVKIT#