TIDUEA0A March   2019  – September 2020

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 Device Recommendation
      2. 2.3.2 Digital Temperature Sensor - TMP117
      3. 2.3.3 Digital Temperature Sensor - TMP116
      4. 2.3.4 ESD Protection Devices
    4. 2.4 System Design Theory
      1. 2.4.1 PT100, PT500, PT1000 based Measurement in Heat Meters
      2. 2.4.2 TMP117 Configuration as Temperature Sensor
      3. 2.4.3 Digital RTD Solution Using TMP117
      4. 2.4.4 Ambient Temperature Considerations
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware and Software
      1. 3.1.1 Hardware
      2. 3.1.2 Interface Test Software for TMP116
    2. 3.2 Testing and Results
      1. 3.2.1 Test Setup for Performance Testing
      2. 3.2.2 EMI and EMC Test Requirements for DRTD
      3. 3.2.3 TMP117 EMI/EMC Test Results
      4. 3.2.4 TMP117 Based Temperature Probe Measurement Performance Test Results
      5. 3.2.5 TMP116 Based Temperature Probe Measurement Performance Test Results
      6. 3.2.6 I2C-bus Cable Length Considerations
      7. 3.2.7 Power Supply
      8. 3.2.8 ESD Test Results for TMP116
      9. 3.2.9 Summary
  9. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 Layout Prints
    4. 4.4 Altium Project
    5. 4.5 Gerber Files
    6. 4.6 Assembly Drawings
  10. 5Software Files
  11. 6Related Documentation
    1. 6.1 Trademarks
  12. 7About the Author
  13. 8Revision History

2.4.4 Ambient Temperature Considerations

The TIDA-010002 is proposed as a replacement of standard analog RTD sensors, which use thin-film passive components and are popular in Heat and Cooling Meters. The design is expected to operate at high ambient temperature and experience multiple cycles changing from "hot" to "cold" and vice versa over its lifetime. Note that TMP117 datasheet specifies that the long-term stability and drift are tested at 300 hours at 150°C and are typically in the range of ±0.05°C.

Furthermore, the TMP117 datasheet specifies the temperature cycling and hysteresis accuracy of ±1 LSB with 8 averages. Such cycling is defined as the ability to reproduce a temperature reading as the temperature varies from room → hot → room → cold → room. The temperatures used for this test are –40°C, 25°C, and 125°C as per the datasheets.

To take full advantage of the industrial temperature range of the TMP117 device, the supply voltage capacitor C1, the optional VDD filter resistor (not present in the TIDA-010002), and any resistors used for I2C address configuration (see R3 and R4 in Section 4.1) should also cover the wide temperature range of –55°C to 150°C, as well as the PCB material used.

For volume production with a fixed I2C slave address, the TIDA-010002 reference design can be modified and the ADD0 pin can be hard-wired to GND, VDD, SDA or SCL lines. Thus R3 and R4 will be removed for further cost saving and improved system reliability.

Class AA and Class A resistance thermometers are defined in EN 60751:2008 within the temperature ranges of 0°C to 150°C and –30°C to 300°C respectively. The TIDA-010002 has a recommended operating free-air temperature down to –55°C, exceeding the minimum temperature limits of both Class A and AA.

The maximum operating temperature is 150°C with TMP117 as used in this Reference Design and is suitable for multiple industrial applications, not only metering.