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

2.3.3 PPG Measurement

For PPG measurement, three LEDs and two PDs are used in a single package. Table 2-2 lists details about the OCS112 (from Taiwan Biophotonic Co.) and SFH7072 (from OSRAM®).

Table 2-2 Optical Sensors
SENSOROCS112SFH7072
Number of LEDs34
Number of PDs12
LED1 colorRedGreen
LED1 wavelength655 nm526 nm
LED2 colorIRGreen
LED2 wavelength945 nm526 nm
LED3 colorGreenRed
LED3 wavelength525 nm660 nm
LED4 color–IR
LED3 wavelength–950 nm
LED1 VF (typ)2.11.3
LED1 VF (max)2.41.8
LED2 VF (typ)1.42.1
LED2 VF (max)1.552.8
LED3 VF (typ)3.23
LED3 VF (max)3.73.4
LED4 VF (typ)–3
LED4 VF (max)–3.4

The Sensor boards are designed to fit on the main board with 5-pin connectors, based on the LEDs and PDs available in the Optical Sensor. All the LEDs are configured in push-pull (common anode mode). See Figure 2-6 and Figure 2-7 for the connection diagrams.

GUID-97CE0B90-0D0A-4CBC-8AD6-63B3252D2BF9-low.gifFigure 2-6 Sensor Board Schematic With SFH7072 Device
GUID-EC11D477-1B7F-4269-ACD1-4EABC771D56D-low.gifFigure 2-7 Sensor Board Schematic With OCS112 Device

The Sensor boards are fit onto the main board using the J1 and J2 connector, as shown in Figure 2-8.

GUID-F9BCD362-5569-4BB5-B694-FCC5CC46F23E-low.gifFigure 2-8 PPG Connection From Sensor Board to AFE4900 Device on Main Board

The J1 connector has 5 connections: TX_SUP, TX drive pins, and GND. The J2 connector has 5 connections: PD1 Anode and Cathode, PD2 Anode and Cathode, and GND. The connector inputs are protected using ESD diodes (TPD1E10B06DPYR) from Texas Instruments. The TPD1E10B06 device is a single-channel, ESD, TVS diode in a small 0402 package. This TVS protection product offers ±30-kV contact ESD, ±30-kV IEC air-gap protection, and an ESD clamp circuit with a back-to-back TVS diode for bipolar or bidirectional signal support. The TX_SUP pin is decoupled using a 33-µF capacitor.

The PD signals are filtered using SMD Common Mode Chokes (having specifications as 90 Ω at 100 MHz, 370-mA DCR 300 mΩ). The chokes help in improving the immunity to external common mode noise signals and improve overall SNR of the system.