TIDUEY7 July   2021

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1  System Control and Processing
      2. 2.2.2  Analog Front End
      3. 2.2.3  Input Voltage Monitoring: 5 V, 20 V, 40 V, and ±5 V
      4. 2.2.4  Bidirectional Current Sense: ±2 A
      5. 2.2.5  Unipolar Current Sense: 0.25 A to 1 A
      6. 2.2.6  TMP461-SP: Local and Remote Temperature Sensing
      7. 2.2.7  NTC Thermistor Temperature Sensing
      8. 2.2.8  Adjustable Voltage Source
      9. 2.2.9  Fixed Output Current Source
      10. 2.2.10 Adjustable 4-mA Current Source
      11. 2.2.11 Power Tree and Power Sequencing
    3. 2.3 Highlighted Products
      1. 2.3.1  MSP430FR5969-SP
      2. 2.3.2  ADC128S102QML-SP
      3. 2.3.3  DAC121S101QML-SP
      4. 2.3.4  LMP7704-SP
      5. 2.3.5  INA901-SP
      6. 2.3.6  LM4050QML-SP
      7. 2.3.7  LM158QML-SP
      8. 2.3.8  LM139QML-SP
      9. 2.3.9  TMP461-SP
      10. 2.3.10 TPS7A4501-SP
      11. 2.3.11 TPS7H2201-SP
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware and Software
      1. 3.1.1 Hardware
      2. 3.1.2 Software
    2. 3.2 Test Setup
      1. 3.2.1 Voltage Monitor Test Setup
      2. 3.2.2 Current Monitor Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Voltage Measurement - Noise Floor Results
      2. 3.3.2 Voltage Measurement - Linearity Results
      3. 3.3.3 Current Measurement - Noise Floor Results
      4. 3.3.4 Current Measurement - Linearity Results
      5. 3.3.5 Analog Outputs
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Documentation Support
    3. 4.3 Support Resources
    4. 4.4 Trademarks
  10. 5About the Author

2.2.2 Analog Front End

The TIDA-010197 demonstrates two different approaches for the analog front end (AFE). The first option is to use an external ADC paired with the MSP430FR5969-SP. The second option is to use the integrated ADC in the MSP430FR5969-SP allowing for a smaller solution size.

The first option uses the 12-bit SAR ADC, ADC128S102QML-SP, which offers a high accuracy and speeds with a FSR of 5 V. The second option uses the integrated ADC, which is a 12-bit SAR ADC FSR of 2.5 V.

Selecting a low-power 12-bit SAR ADC like the ADC128S102QML-SP helps to achieve the resolutions and speed needed to meet design goals. Both the external and integrated solutions have the same signal conditioning architecture leading up to the ADC. This includes the components and circuitry associated with the voltage and current measurements, voltage range scaling, current-voltage conversion, signal conditioning, and reference voltage generation. The AFE outputs the resulting voltage and current signals for input to the buffer, gain stage, and ADC, which is interfaced with the MSP430FR5969-SP through an SPI.