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 System Overview

Heat Meters are typically powered by one Lithium primary battery cell and must operate for at least 6 years or longer, depending on the ambient temperature conditions and the number of wireless communication packets transmitted during a specific time period. Therefore, a key product design consideration is the lowest possible power consumption.

Heat and Cooling Meters use a DTM subsystem to measure the temperature every few seconds (or less frequently) of two flows of an opposite direction, which allows to power off the DTM circuitry for most of the measurement cycle. Besides the highly-accurate temperature measurement, the energy consumption of these meters is minimized by the ability to quickly wake from power-down mode, measure the temperature of two RTDs and return to power-down mode as quickly as possible.

The TMP117 device features a very short power-up or reset period of only 1.5 ms typical, a conversion measurement cycle of 15.5 ms, a highly-accurate 0.0078125°C temperature resolution, and a Fast-Mode (400 kHz) I2C-bus communications interface. All of these enable the power on-off cycling of the TIDA-010002 between measurement cycles.

This Digital RTD solution saves processing time on the host MCU, as the linearization of the measurement result and conversion to a temperature value is done inside the TMP117 device.