MAX31865

Part: MAX31865 — Maxim Integrated

Type: Resistance-to-Digital Converter

Description: 15-bit precision delta-sigma ADC resistance-to-digital converter optimized for PT100 to PT1000 platinum RTDs with ±45 V input fault protection and SPI-compatible interface.

Operating Conditions:

• Supply voltage: 3.0 to 3.6 V (VDD and DVDD)
• Operating temperature: -40 to +125 °C
• SCLK frequency: DC to 5.0 MHz

Absolute Maximum Ratings:

• Max supply voltage: 4.0 V (VDD relative to GND1, DVDD relative to DGND)
• Max continuous current: 2758.6 mW continuous power dissipation (TQFN, TA = +70 °C), 952.4 mW continuous power dissipation (SSOP, TA = +70 °C)
• Max junction/storage temperature: +150 °C junction, -65 to +150 °C storage

Key Specs:

• ADC Resolution: 15 Bits (no missing codes)
• Total Accuracy: 0.5 °C max (0.05% of full scale) over all operating conditions
• Bias Voltage (VBIAS): 1.95 V min, 2.00 V typ, 2.06 V max
• Bias Voltage Output Current: 0.2 mA min, 5.75 mA max
• Single Conversion Time: 52 ms typ, 55 ms max (60 Hz notch); 62.5 ms typ, 66 ms max (50 Hz notch)
• Continuous Conversion Time: 16.7 ms typ, 17.6 ms max (60 Hz notch); 20 ms typ, 21 ms max (50 Hz notch)
• Active Conversion Supply Current (IDD): 2 mA typ, 3.5 mA max (bias on, active conversion)
• Shutdown Supply Current (IDD Shutdown): 1.5 mA typ, 3 mA max (bias off, ADC off)
• 50/60 Hz Noise Rejection: 82 dB typ

Features:

• Supports 100 Ω to 1 kΩ (at 0 °C) platinum RTDs (PT100 to PT1000)
• Compatible with 2-, 3-, and 4-wire sensor configurations
• ±45 V overvoltage input protection on sensor terminals
• Integrated fault detection for open RTD, cable faults, and short circuits
• Fully differential VREF and analog inputs
• SPI-compatible serial interface

Applications:

• Industrial Equipment
• Medical Equipment
• Instrumentation

Package:

• 20-Pin TQFN
• 20-Pin SSOP

• Integration Lowers System Cost, Simplifies Design Efforts, and Reduces Design Cycle Time
• Simple Conversion of Platinum RTD Resistance to Digital Value
• Handles 100 Ω to 1k Ω (at 0°C) Platinum RTDs (PT100 to PT1000)
• Compatible with 2-, 3-, and 4-Wire Sensor Connections
• SPI-Compatible Interface
• 20-Pin TQFN and SSOP Packages
• High Accuracy Facilitates Meeting Error Budgets
• 15-Bit ADC Resolution; Nominal Temperature Resolution 0.03125 N C (Varies Due to RTD Nonlinearity)
• Total Accuracy Over All Operating Conditions: 0.5 N C (0.05% of Full Scale) max
• Fully Differential V REF Inputs
• 21ms (max) Conversion Time
• Integrated Fault Detection Increases System Reliability
• ±45V Input Protection
• Fault Detection (Open RTD Element, RTD Shorted to Out-of-Range Voltage, or Short Across RTD Element)

• Industrial Equipment
• Medical Equipment
• Instrumentation

Ordering Information appears at end of data sheet.

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(3.0V P V DD P 3.6V, T A = -40 N C to +125 N C, unless otherwise noted. Typical values are T A = +25 N C, V DD = V DVDD = 3.3V.) (Notes 2 and 3)

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Stresses beyond those listed under 'Absolute Maximum Ratings' may cause permanent damage to the device. These are stress ratings only, and functional operation 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.

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.maximintegrated.com/thermal-tutorial .

• Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

*EP = Exposed pad.

For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.