SLAA957 September   2020 MSP430AFE221 , MSP430AFE222 , MSP430AFE223 , MSP430AFE231 , MSP430AFE232 , MSP430AFE233 , MSP430AFE251 , MSP430AFE252 , MSP430AFE253 , MSP430F2003 , MSP430F2013 , MSP430F2013-EP , MSP430F423A , MSP430F4250 , MSP430F425A , MSP430F4260 , MSP430F4270 , MSP430F427A , MSP430F47126 , MSP430F47127 , MSP430F47163 , MSP430F47166 , MSP430F47167 , MSP430F47173 , MSP430F47176 , MSP430F47177 , MSP430F47183 , MSP430F47186 , MSP430F47187 , MSP430F47193 , MSP430F47196 , MSP430F47197 , MSP430F477 , MSP430F478 , MSP430F4783 , MSP430F4784 , MSP430F479 , MSP430F4793 , MSP430F4794 , MSP430F6720 , MSP430F6720A , MSP430F6721 , MSP430F6721A , MSP430F6723 , MSP430F6723A , MSP430F6724 , MSP430F6724A , MSP430F6725 , MSP430F6725A , MSP430F6726 , MSP430F6726A , MSP430F6730 , MSP430F6730A , MSP430F6731 , MSP430F6731A , MSP430F6733 , MSP430F6733A , MSP430F6734 , MSP430F6734A , MSP430F6735 , MSP430F6735A , MSP430F6736 , MSP430F6736A , MSP430F6745 , MSP430F67451 , MSP430F67451A , MSP430F6745A , MSP430F6746 , MSP430F67461 , MSP430F67461A , MSP430F6746A , MSP430F6747 , MSP430F67471 , MSP430F67471A , MSP430F6747A , MSP430F6748 , MSP430F67481 , MSP430F67481A , MSP430F6748A , MSP430F6749 , MSP430F67491 , MSP430F67491A , MSP430F6749A , MSP430F67621 , MSP430F67621A , MSP430F67641 , MSP430F67641A , MSP430F6765 , MSP430F67651 , MSP430F67651A , MSP430F6765A , MSP430F6766 , MSP430F67661 , MSP430F67661A , MSP430F6766A , MSP430F6767 , MSP430F67671 , MSP430F67671A , MSP430F6767A , MSP430F6768 , MSP430F67681 , MSP430F67681A , MSP430F6768A , MSP430F6769 , MSP430F67691 , MSP430F67691A , MSP430F6769A , MSP430F6775 , MSP430F67751 , MSP430F67751A , MSP430F6775A , MSP430F6776 , MSP430F67761 , MSP430F67761A , MSP430F6776A , MSP430F6777 , MSP430F67771 , MSP430F67771A , MSP430F6777A , MSP430F6778 , MSP430F67781 , MSP430F67781A , MSP430F6778A , MSP430F6779 , MSP430F67791 , MSP430F67791A , MSP430F6779A , MSP430FE423 , MSP430FE4232 , MSP430FE423A , MSP430FE4242 , MSP430FE425 , MSP430FE4252 , MSP430FE425A , MSP430FE427 , MSP430FE4272 , MSP430FE427A , MSP430FG4250 , MSP430FG4260 , MSP430FG4270 , MSP430FG477 , MSP430FG478 , MSP430FG479 , MSP430FG6425 , MSP430FG6426 , MSP430FG6625 , MSP430FG6626 , MSP430FR5041 , MSP430FR5043 , MSP430FR50431 , MSP430FR6005 , MSP430FR6007 , MSP430FR6041 , MSP430FR6043 , MSP430FR60431 , MSP430FR6045 , MSP430FR6047 , MSP430FR60471 , MSP430I2020 , MSP430I2021 , MSP430I2030 , MSP430I2031 , MSP430I2040 , MSP430I2041

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction: MSP Sigma-Delta ADCs and Common Applications
  4. 2MSP Sigma-Delta ADC Portfolio
  5. 3Sigma-Delta ADC Overview
  6. 4MSP Sigma-Delta ADC Features
    1. 4.1  ADC Inputs: Differential or Single-Ended
    2. 4.2  Input Channels: Independent or Multiplexed
    3. 4.3  Integrated Buffers
    4. 4.4  Integrated PGAs
    5. 4.5  Offset Calibration: Internal or External
    6. 4.6  Voltage Reference: Internal or External
    7. 4.7  ADC Modulator Clock Frequency: Fixed or Adjustable
    8. 4.8  Sampling Rate versus Data Rate
    9. 4.9  Conversion Mode: Single or Continuous
    10. 4.10 Groups of ADC Channels
    11. 4.11 Preload
    12. 4.12 Output Format: Unipolar or Bipolar Data
    13. 4.13 Module Synchronization
    14. 4.14 Architecture: Discrete-Time versus Continuous-Time
  7. 5Solutions to Common MSP Sigma-Delta ADC Configuration Issues
    1. 5.1 ADC Input Configuration
      1. 5.1.1 Settling Time Exceeds Recommended Minimum
      2. 5.1.2 Amplitude of the Input Signal Exceeds FSR
      3. 5.1.3 Missing Anti-Aliasing Filters
    2. 5.2 ADC Clocking Configuration
      1. 5.2.1 Incorrect Sampling Frequency
    3. 5.3 ADC Results
      1. 5.3.1 Unexpected Output Data Format
      2. 5.3.2 Low Resolution
      3. 5.3.3 Data Interpretation
    4. 5.4 Reference Module (REF) Configuration
      1. 5.4.1 Choosing Between an Internal or External Reference
      2. 5.4.2 Connecting the Recommended Capacitors
      3. 5.4.3 Delaying Conversions Until the Reference Settles
    5. 5.5 Hardware Recommendations
  8. 6Frequently Asked Questions
  9. 7References

4.5 Offset Calibration: Internal or External

The SD ADC modules in Table 2-1 except SD24 and SDHS include a feature that simplifies the PGA offset calibration. Rather than shorting the ADC inputs together externally, an internal short can be enabled via software to easily measure this offset, even if an external circuit is connected. After calibration, the positive or negative offset would be manually subtracted to or added from the digital output, respectively.