MAX31855PMB1 Peripheral Module
_________________________________________________________________ Maxim Integrated Products 1
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.
General Description
The MAX31855PMB1 peripheral module provides the
necessary hardware to interface the MAX31855 cold-
junction compensated thermocouple-to-digital converter
to any system that utilizes PmodK-compatible expansion
ports. The IC performs cold-junction compensation and
digitizes the signal from a thermocouple. Versions of the
IC are available that operate with a K-, J-, N-, T-, R-, or
E-type thermocouple. This module is set up to operate
with a K-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 Q2NC for temperatures ranging from
-200NC to +700NC for K-type thermocouples.
For full range accuracies, other thermocouple types, and
detailed information regarding operation of the IC, r
efer to
the MAX31855 IC data sheet.
Note: K-type thermocouple is not included with Maxim
Peripheral Module collections.
Features
S Converts Output of a K-Type Thermocouple
Directly to a Signed 14-Bit Digital Word
S Cold-Junction Compensation
S 14-Bit, 0.25NC Resolution
S Detects Thermocouple Shorts to GND or VCC
S Detects Open Thermocouple
S 6-Pin Pmod-Compatible Connector (SPI)
S Example Software Written in C for Portability
S RoHS Compliant
S Proven PCB Layout
S Fully Assembled and Tested
MAX31855PMB1 Photo
19-6333; Rev 0; 5/12
Ordering Information appears at end of data sheet.
Pmod is a trademark of Digilent Inc.
_________________________________________________________________ Maxim Integrated Products 2
MAX31855PMB1 Peripheral Module
Component List
*Thermocouple not included with Maxim peripheral module
collections.
Component Suppliers
Note: Indicate that you are using the MAX31855PMB1 when contacting these component suppliers.
Detailed Description
SPI Interface
The MAX31855PMB1 peripheral module can plug directly
into a Pmod-compatible port (configured for SPI) through
connector J1. For information on the SPI protocol, refer to
the MAX31855 IC data sheet.
Connector J1 provides connection of the module to
the Pmod host. The pin functions and pin assignments
adhere to the Pmod standard recommended by Digilent.
See Table 1.
Software and FPGA Code
Example software and drivers are available that execute
directly without modification on several FPGA develop-
ment boards that support an integrated or synthesized
microprocessor. These boards include the Digilent Nexys
3, Avnet LX9, and Avnet ZEDBoard, although other plat-
forms can be added over time. Maxim provides complete
Xilinx ISE projects containing HDL, Platform Studio, and
SDK projects. In addition, a synthesized bitstream, ready
for FPGA download, is provided for the demonstration
application.
The software project (for the SDK) contains several
source files intended to accelerate customer evalu-
ation and design. These include a base application
(maximModules.c) that demonstrates module function-
ality and uses an API interface (maximDeviceSpecific
Utilities.c) to set and access Maxim device functions
within a specific module.
The source code is written in standard ANSI C format, and
all API documentation including theory/operation, register
description, and function prototypes are documented in
the API interface file (maximDeviceSpecificUtilities.h & .c).
The complete software kit is available for download at
www.maxim-ic.com. Quick start instructions are also
available as a separate document.
Table 1. Connector J1 (SPI Communication)
DESIGNATION QTY DESCRIPTION
C1, C4 0 Not installed, ceramic capacitors
(0805)
C2 1
0.1FF Q10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C104KA01D
C3 1
0.01FF Q10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C103KA01D
D1 1 TVS diode (3 SOT3)
ON Semi NUP2105TL1G
J1 1 6-pin right-angle male header
DESIGNATION QTY DESCRIPTION
J2 1 K-type thermocouple socket
Omega PCC-SMP-K-5-ROHS
L1, L2 2 470I ferrite beads (0603)
Murata BLM18PG471SN1D
R1, R2, R3 3 150I Q5% resistors (0603)
U1 1
Thermocouple to digital IC
(8 SO)
Maxim MAX31855KASA+
— 1 K-type thermocouple, mini plug*
— 1 PCB: EPCB31855PM1
SUPPLIER PHONE WEBSITE
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
Omega Engineering 888-826-6342 www.omega.com
ON Semiconductor 602-244-6600 www.onsemi.com
PIN SIGNAL DESCRIPTION
1 SS Chip enable. Must be asserted low to
enable the SPI interface.
2 N.C. Not connected
3 MISO Serial-data output
4 SCK Serial-clock input
5 GND Ground
6 VCC Power supply
_________________________________________________________________ Maxim Integrated Products 3
MAX31855PMB1 Peripheral Module
Figure 1. MAX31855PMB1 Peripheral Module Schematic
VCCGND
GND
1
T-
2
T+
3
VCC
4SCK5
CS 6
SO 7
DN C8
MAX3 1855U1
0. 01uF
C3
Do Not Install
C1
Do Not Install
C4
470ohm Ferrite Bead
L1
Omega PCC-SMP-K-5-RO HS so cket
1
2
3
NUP2 105L
D1
POS
NEGNC2
NC1
THERMOCOUPLE CONN ECTO R
J2
T+
T-
T-
T+
VCC
GND
MISO
SS
SCK
GND
GND
GND
SS
SCK
MISO
GND
VCC
15 0R1
15 0R3
1
2
3
4
5
6
J1
0. 1uF
C2
470ohm Ferrite Bead
L2
15 0R2
_________________________________________________________________ Maxim Integrated Products 4
MAX31855PMB1 Peripheral Module
Figure 2. MAX31855PMB1 Peripheral Module Component Placement Guide—Component Side
Figure 3. MAX31855PMB1 Peripheral Module PCB Layout—Component Side
Figure 4. MAX31855PMB1 Peripheral Module PCB Layout—Inner Layer 1 (Ground)
_________________________________________________________________ Maxim Integrated Products 5
MAX31855PMB1 Peripheral Module
Figure 5. MAX31855PMB1 Peripheral Module PCB Layout—Inner Layer 2 (Power)
Figure 6. MAX31855PMB1 Peripheral Module PCB Layout—Solder Side
Figure 7. MAX31855PMB1 Peripheral Module Component Placement Guide—Solder Side
_________________________________________________________________ Maxim Integrated Products 6
MAX31855PMB1 Peripheral Module
Ordering Information
#Denotes RoHS compliant.
PART TYPE
MAX31855PMB1# Peripheral Module
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 7
© 2012 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX31855PMB1 Peripheral Module
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 5/12 Initial release —
