TIDUDO6B May   2019  – October 2020

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Introduction to Parameters Measured Using TIDA-01580
    2. 1.2 High-Level System Description
    3. 1.3 Typical Applications
    4. 1.4 System Specifications and Design Features
    5. 1.5 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 AFE4900
      2. 2.2.2 CC2640R2F
      3. 2.2.3 TPS61099
      4. 2.2.4 TPS63036
      5. 2.2.5 TPD1E10B06
    3. 2.3 System Design Theory and Design Considerations
      1. 2.3.1  AFE4900 and Power Supply
      2. 2.3.2  CC2640R2F Microcontroller
      3. 2.3.3  PPG Measurement
      4. 2.3.4  ECG Measurement
        1. 2.3.4.1 Two-Electrode Configuration
        2. 2.3.4.2 Three-Electrode Configuration
      5. 2.3.5  Selecting TX Supply (TX_SUP) Value for Driving LEDs
      6. 2.3.6  Generating TX Supply for Driving LEDs
        1. 2.3.6.1 Programming Output Voltage
        2. 2.3.6.2 Maximum Output Current
        3. 2.3.6.3 Input and Output Capacitor Selection
        4. 2.3.6.4 Switching Frequency
        5. 2.3.6.5 WEBENCH® Simulation for TPS61099 Boost Converter
      7. 2.3.7  Generating RX Supply for AFE4900
        1. 2.3.7.1 Setting Output Voltage
        2. 2.3.7.2 Capacitor Selection
        3. 2.3.7.3 Output Current Limit
        4. 2.3.7.4 Inductor Selection
        5. 2.3.7.5 TINA-TI™ Simulation for TPS63036
      8. 2.3.8  Generating I/O Supply
      9. 2.3.9  Battery Input and Reservoir Capacitors
      10. 2.3.10 Battery Life Calculations
        1. 2.3.10.1 AFE4900 Current Consumption
        2. 2.3.10.2 CC2640R2F Current Consumption
        3. 2.3.10.3 On-State Current Calculations
        4. 2.3.10.4 Off-State Current Calculations (Considering Battery Voltage = 3 V)
      11. 2.3.11 External Memory
      12. 2.3.12 LED Indications
      13. 2.3.13 Connections Between Sensor Board and ECG Board
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware and Software
      1. 3.1.1 Hardware
        1. 3.1.1.1 Connecting Optical Sensor and ECG Boards to Main Board
        2. 3.1.1.2 Difference Between PPG Sensor Boards
      2. 3.1.2 Software
        1. 3.1.2.1 Software Loading for TIDA-01580 Board (Transmit Side of BLE)
        2. 3.1.2.2 LabVIEW™ File Execution for Checking Measurement Data (Receive Side of BLE)
    2. 3.2 Testing and Results
      1. 3.2.1 Test Setup
      2. 3.2.2 Test Results
        1. 3.2.2.1 Heart-Rate Measurement Using PPG (Green LED) and ECG
        2. 3.2.2.2 SpO2 Measurement Using Red and IR LEDs
        3. 3.2.2.3 PTT Measurement
        4. 3.2.2.4 Lead-Off Detect
          1. 3.2.2.4.1 AC Lead-Off Detect
          2. 3.2.2.4.2 DC Lead-Off Detect
        5. 3.2.2.5 Low-Battery Indication
        6. 3.2.2.6 Waveforms for DC/DC Converters
        7. 3.2.2.7 Battery Life Test
  9. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 PCB Layout Recommendations
      1. 4.3.1  Layout for Main Board
      2. 4.3.2  Connection From PDs to AFE
      3. 4.3.3  Connections From LEDs to AFE
      4. 4.3.4  Connections From ECG PADs to AFE
      5. 4.3.5  Connections Between BT and AFE
      6. 4.3.6  Connections Between BT Antenna and Chip
      7. 4.3.7  Boost Converter
      8. 4.3.8  Buck-Boost Converter
      9. 4.3.9  Layouts for PPG Sensor Boards
      10. 4.3.10 Layout for ECG Sensor Board
      11. 4.3.11 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 Authors
  13.   Revision History

2.3.9 Battery Input and Reservoir Capacitors

The power source for this TIDA-01580 device is the CR3032, a lithium-ion coin cell. Selection of the CR2032 coin-cell battery as the power source was due to the ubiquity of the battery type, particularly in small form factor systems. The voltage characteristics of the CR3032 lithium-ion coin cell battery are also ideal. The output voltage remains relatively flat throughout the discharge life, until the cell is nearly depleted. When the remaining charge in the coin-cell battery is nearly depleted, the output voltage drops off relatively quickly. The temperature characteristics of lithium-ion batteries are also superior to that of alkaline cells, particularly at lower temperatures. This superiority is due to lithium-ion cells having a non-aqueous electrolyte that performs better than the aqueous electrolytes commonly found in alkaline batteries.

GUID-4D4499E6-EB0E-4B7B-A80C-B16F811D524D-low.gifFigure 2-18 Battery Connector and Reservoir

Given an appropriate weather-proof enclosure, this TI reference design system is suited for both indoor and outdoor use. Immediately following the battery is a bulk capacitor. This TI reference design uses a coin-cell battery tray that prevents an end-user from inserting the battery backwards, which may eliminate the need for the reverse Schottky diode. The bulk capacitor is sized to prevent too much voltage sag, particularly during the initial transition into the on state (see Figure 2-18).