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

2.3.10.1 AFE4900 Current Consumption

The current consumption of the AFE4900 device depends on the sampling rate (for example, PTT mode at 1-kHz sampling rate for both ECG and PPG).

Typical specifications are at TA = 25°C; TX_SUP = 5 V, RX_SUP = 1.8 V (with CONTROL1 = 1.8 V to bypass internal LDOs), IO_SUP = 1.8 V, external clock mode with 32-kHz clock on CLK pin (period = tTE = 31.25 µs), the AFE operates with ULP mode enabled (ENABLE_ULP = 1); PPG: 1-kHz sampling rate, SAMP width of 3 × tTE, LED ON width of 4 × tTE, CF chosen such that there are 7-8 TIA time constants within the SAMP width, NUMAV = 1 (2 ADC averages), noise-reduction filter bandwidth set to 2.5 kHz, CIN = 100 pF (capacitor across the input pins to model the zero bias differential capacitance of the PD); ECG: 1-kHz sampling rate, INA gain of 12, chopper mode enabled (unless otherwise noted).

Table 2-8 Current Consumption for AFE4900 in Different Modes
PARAMETERTEST CONDITIONSMINTYPMAXUNIT
CURRENT CONSUMPTION
RX_SUP current excluding switching current from I2C or SPI readout(5)Low PRF PPG signal acquisition(3)50µA
High PRF ECG, PPG signal acquisition(4)600
Hardware power-down (PWDN) mode(2)< 1
Software power-down (PDNAFE) mode(2)15
RX_SUP current resulting from switching current at I2C readoutAt PRF of 50 Hz, readout with FIFO enabled with FIFO_PERIOD = 60,
FIFO_NPHASE = 4(6)		6µA
Power-down mode0
IO_SUP currentLow PRF, PPG signal acquisition(3)1µA
High PRF, ECG, PPG signal acquisition(3)1
Hardware power-down (PWDN) mode(2)< 1
Software power-down (PDNAFE) mode(2)< 1
TX_SUP currentLow PRF, PPG signal acquisition(3)4µA
High PRF, ECG, PPG signal acquisition(4)20
Hardware power-down (PWDN) mode(2)(1)< 1
Software power-down (PDNAFE) mode(2)(1)< 1
DIGITAL INPUTS
VIHHigh-level input voltageDigital inputs except CONTROL1, I2C_SPI_SEL0.9 × IO_SUPIO_SUPV
CONTROL1 and I2C_SPI_SEL(7)0.85 × RX_SUPRX_SUP
VILLow-level input voltageDigital inputs except CONTROL1, I2C_SPI_SEL00.1 × IO_SUPV
CONTROL1 and I2C_SPI_SEL(7)00.1 × RX_SUP
DIGITAL OUTPUTS
VOHHigh-level output voltageIO_SUPV
VOLLow-level output voltage0V
(1) With LED currents set to 0 mA
(2) External clock switched off.
(3) Acquisition of four phases of signal in PPG mode at 50-Hz PRF.
(4) PTT mode at 1-kHz sampling rate for both ECG and PPG
(5) The additional current for FIFO readout is negligible when operating in the SPI mode.
(6) This current depends on the percentage of time for which the I2C_CLK is low; and scales with FIFO_NPHASE and PRF. This extra component of current is negligible when operating in the SPI interface mode.
(7) CONTROL1 and I2C_SPI_SEL can also be driven directly by the MCU (with IO_SUP levels) if the VIH, VIL levels are satisfied.
GUID-F8DB2D00-717D-470D-BB19-645F48D7A218-low.gifFigure 2-19 Current Consumption for AFE4900 in LDO Enable Mode

The TX_SUP current is taken to be 3 mA at normal operating conditions (10% duty cycle for 100 mA) – worst case.

Over operating free-air temperature range (unless otherwise noted).

Table 2-9 LED Drive Currents With Duty Cycles
PARAMETER(1)(2)MINMAXUNIT
Supply voltage rangeRX_SUP to GND
LDO bypassed		–0.32.1V
RX_SUP to GND
LDO enabled(3)		–0.34
IO_SUP to GND–0.3Min [4,(RX_SUP+0.3)]
TX_SUP to GND–0.36
Voltage applied to analog inputsMax [–0.3, (GND – 0.3)]Min [4.0, (RX_SUP + 0.3)]V
Voltage applied to digital inputsMax [–0.3, (GND – 0.3)]Min [4.0, (IO_SUP + 0.3)]V
Maximum duty cycle (cumulative): sum of all LED phase durations as a function of the total period50-mA LED current10%
100-mA LED current3%
200-mA LED current1%
Junction temperature, TJ105°C
Storage temperature, Tstg–60150°C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) If subjected to additional processing steps (for example during PCB assembly or product manufacturing), avoid exposure of the device to UV radiation and exposure to high temperatures (350°C and higher).
(3) Voltages higher than 2.1 V can be applied on RX_SUP only when CONTROL1 pin is at 0.

The RX_SUP and IO_SUP current are taken to be 700 µA (600 µA + 10 µA (I/O) + 50 µA (LDO enabled) + 40 µA (buffer)).