TIDUF16 December   2023

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Photodiode, TIA, and ADC
      2. 2.2.2 LED Driving
      3. 2.2.3 Power
      4. 2.2.4 Display, Orientation, and Communication Features
      5. 2.2.5 Software
        1. 2.2.5.1 Timing Structure
        2. 2.2.5.2 Oversampling and Digital Filtering to Increase Dynamic Range
        3. 2.2.5.3 Calculating Vitals
    3. 2.3 Highlighted Products
      1. 2.3.1 MSPM0L1306
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Software Requirements
      1. 3.2.1 TI GUI
      2. 3.2.2 CCS Project
      3. 3.2.3 Analog Engineers Calculator
    3. 3.3 Test Setup
    4. 3.4 Test Results
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks

2.2.1 Photodiode, TIA, and ADC

In TIDA-010267, the photodiodes signal, in the form of a current on the order of nano-Amps is converted to a voltage and amplified to fit in the range of the ADC of the MSPM0L1306. This is achievable using the low input bias current of the integrated OPA, allowing the design to utilize the OPA as a TIA, as shown in Figure 2-5. Using the MSPM0L1306 voltage input as a reference for the high-speed ADC, the convertor can more rapidly sample, which allows for oversampling and reduced LED on-time. An internal voltage monitoring feature in between samples, allows the MSPM0L1306 to quantify the level of the incoming signal and adjust parameters accordingly. Further features, such as internal temperature sensing, are also possible.