TIDUEO0C July   2019  – March 2021

 

  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 TPS63900: 1.8V-5.5 VIN Buck-Boost Converter With 75-nA Ultra-low Quiescent Current and 400-mA Output Current
      2. 2.3.2 TPS610995: 0.7 VIN Synchronous Boost Converter With 400-nA Ultra-low Quiescent Current and 1-A Peak Current
      3. 2.3.3 TPS62840: 750-mA Synchronous Step-Down Converter With Ultra-low Quiescent Current Consumption
    4. 2.4 System Design Theory
      1. 2.4.1 Battery Gauge BQ35100
      2. 2.4.2 In-System Current Monitoring
        1. 2.4.2.1 Resistor Values Calculation for the two Current Ranges
        2. 2.4.2.2 LPV521 Gain Calculation
        3. 2.4.2.3 Current Ranges Simulation With TINA-TI
        4. 2.4.2.4 Key ADS7142 Register Settings in TIDA-01546 Firmware
          1. 2.4.2.4.1 ADS7142 Sampling Rate
      3. 2.4.3 NB-IoT Module From u-blox
      4. 2.4.4 NB-IoT Module From Quectel
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware
      1. 3.1.1 Testing TIDA-010053
      2. 3.1.2 TPS62840 Subsystem
      3. 3.1.3 TPS610995 Subsystem
      4. 3.1.4 Software
    2. 3.2 Testing and Results
      1. 3.2.1 Test Setup
      2. 3.2.2 Test Results
        1. 3.2.2.1 Test Results With the TPS62840 Buck Converter
        2. 3.2.2.2 Test Results With the TPS610995 Boost Converter
        3. 3.2.2.3 Test Results With the TPS63900 Buck-Boost Converter NB
        4. 3.2.2.4 Summary
  9. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 PCB Layout Recommendations
      1. 4.3.1 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. 7Terminology
  13. 8About the Author
  14. 9Revision History

2.4.2 In-System Current Monitoring

The second relevant subsystem of the TIDA-01546 reference design uses the ADS7142 nanopower SAR ADC device, which can measure both a low-current range with 0–10 µA and a high-current range with 0–476 mA current. The range selection is deliberately made, as typically in ultra-low power metrology mode a smart flow meter device uses less than 10 µA average current. The second range for up to 476 mA is used when the smart meter or IoT application is running an NB-IoT communication (or any other wireless communication with the corresponding current profile, for example wM-Bus N-mode transmission in 169 MHz band with up to +25 dBm). These two current profile ranges align quite well with the data sheet values for power-saving mode and active mode for both NB-IoT modules described in Section 2.4.3 and in Section 2.4.4.