MAX31865 Datasheet, PDF (1/25 Pages) Maxim Integrated Products – RTD-to-Digital Converter

EVALUATION KIT AVAILABLE
MAX31865
RTD-to-Digital Converter
General Description
The MAX31865 is an easy-to-use resistance-to-digital
converter optimized for platinum resistance temperature
detectors (RTDs). An external resistor sets the sensitivity
for the RTD being used and a precision delta-sigma ADC
converts the ratio of the RTD resistance to the reference
resistance into digital form. The MAX31865’s inputs are
protected against overvoltage faults as large as Q50V.
Programmable detection of RTD and cable open and
short conditions is included.
Applications
Industrial Equipment
Medical Equipment
Instrumentation
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to www.maximintegrated.com/MAX31865.related.
Features
S Simple Conversion of Platinum RTD Resistance to
Digital Value
S Handles 100Ω to 1kΩ (at 0°C) Platinum RTDs
(PT100 to PT1000)
S Compatible with 2-, 3-, and 4-wire Sensor Connections
S Conversion Time: 21ms max
S 15-Bit ADC Resolution; Nominal Temperature
Resolution 0.03125NC (Varies Due to RTD
Nonlinearity)
S Total Accuracy Over All Operating Conditions:
0.5NC (0.05% of Full Scale) max
S ±50V Input Protection
S Fully Differential V_REF Inputs
S Fault Detection (Open RTD Element, RTD Shorted to
Out-of-Range Voltage, or Short Across RTD Element)
S SPI-Compatible Interface
S 20-Pin TQFN Package
Typical Application Circuits
4-WIRE SENSOR CONNECTION
VDD
0.1µF
VDD
0.1µF
HOST
INTERFACE
DRDY
SDI
SCLK
CS
SDO
N.C.
BIAS
REFIN+
REFIN-
ISENSOR
MAX31865
FORCE+
FORCE2
RTDIN+
RTDIN-
FORCE-
RREF
RCABLE
RCABLE
CI*
RTD
RCABLE
RCABLE
*CI = 10nF FOR 1kΩ RTD
100nF FOR 100Ω RTD
Typical Application Circuits continued at end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-6478; Rev 0; 10/12