SLYY211 October   2021 TMS320F2800132 , TMS320F2800133 , TMS320F2800135 , TMS320F2800137 , TMS320F2800152-Q1 , TMS320F2800153-Q1 , TMS320F2800154-Q1 , TMS320F2800155 , TMS320F2800155-Q1 , TMS320F2800156-Q1 , TMS320F2800157 , TMS320F2800157-Q1 , TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F28075 , TMS320F28075-Q1 , TMS320F28076 , TMS320F28374D , TMS320F28374S , TMS320F28375D , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376D , TMS320F28376S , TMS320F28377D , TMS320F28377D-EP , TMS320F28377D-Q1 , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378D , TMS320F28378S , TMS320F28379D , TMS320F28379D-Q1 , TMS320F28379S

 

  1. 1 Message from the editors
  2. 2 System Design
    1. 2.1 Control
      1. 2.1.1 Open loop versus closed loop
    2. 2.2 Feedback control
      1. 2.2.1 Error ratio
    3. 2.3 Dynamic systems
      1. 2.3.1 First order system
      2. 2.3.2 Second order system
    4. 2.4 System stability
      1. 2.4.1 Gain margin
      2. 2.4.2 Phase margin
    5. 2.5 Timing requirements
      1. 2.5.1 Peak/rise time
      2. 2.5.2 Settling time
      3. 2.5.3 Overshoot
      4. 2.5.4 Damping
      5. 2.5.5 Delay
    6. 2.6 Discrete Time Domain
    7. 2.7 Filters
      1. 2.7.1 Filter Types
      2. 2.7.2 Filter Orders
    8. 2.8 Notes
  3. 3 Controllers
    1. 3.1 Linear PID
    2. 3.2 Linear PI
    3. 3.3 Nonlinear PID
    4. 3.4 2P2Z
    5. 3.5 3P3Z
    6. 3.6 Direct form controllers
      1. 3.6.1 DF11
      2. 3.6.2 DF13
      3. 3.6.3 DF22
      4. 3.6.4 DF23
    7. 3.7 Notes
  4. 4 ADC
    1. 4.1 ADC definitions
    2. 4.2 ADC resolution
      1. 4.2.1 ADC resolution for unipolar
      2. 4.2.2 ADC resolution for differential signals
      3. 4.2.3 Resolution voltage vs. full-scale range
    3. 4.3 Quantization error of ADC
    4. 4.4 Total harmonic distortion (THD)
      1. 4.4.1 Total harmonic distortion (VRMS)
      2. 4.4.2 Total harmonic distortion (dBc)
    5. 4.5 AC signals
    6. 4.6 DC signals
    7. 4.7 Settling time and conversion accuracy
    8. 4.8 ADC system noise
    9. 4.9 Notes
  5. 5 Comparator
    1. 5.1 Basic operation
    2. 5.2 Offset and hysteresis
    3. 5.3 Propagation delay
    4. 5.4 Notes
  6. 6 Processing
    1. 6.1 Data representation
    2. 6.2 Central processing unit
      1. 6.2.1 CPU basics
      2. 6.2.2 CPU pipeline
      3. 6.2.3 Characteristics of a real-time processor
      4. 6.2.4 Signal chain
    3. 6.3 Memory
    4. 6.4 Direct memory access (DMA)
    5. 6.5 Interrupts
    6. 6.6 Co-processors and accelerators
    7. 6.7 Notes
  7. 7 Encoders
    1. 7.1 Encoder definitions
    2. 7.2 Types of encoders
    3. 7.3 Description of encoders
      1. 7.3.1 Linear encoders
      2. 7.3.2 Rotary encoders
      3. 7.3.3 Position encoders
      4. 7.3.4 Optical encoders
    4. 7.4 Absolute Vs incremental encoders
      1. 7.4.1 Absolute rotary encoders
      2. 7.4.2 Incremental encoders
    5. 7.5 Notes
  8. 8 Pulse width modulation (PWM)
    1. 8.1 PWM definitions
    2. 8.2 Duty cycle
    3. 8.3 Resolution
    4. 8.4 Deadband
    5. 8.5 Notes
  9. 9 DAC
    1. 9.1 DAC definitions
    2. 9.2 DAC error
      1. 9.2.1 DAC offset error
      2. 9.2.2 DAC gain error
      3. 9.2.3 DAC zero-code error
      4. 9.2.4 DAC full-scale error
      5. 9.2.5 DAC differential non-linearity (DNL)
      6. 9.2.6 DAC integral non-linearity (INL)
      7. 9.2.7 DAC total unadjusted error (TUE)
    3. 9.3 DAC output considerations
      1. 9.3.1 DAC linear range
      2. 9.3.2 DAC settling time
      3. 9.3.3 DAC load regulation
    4. 9.4 Notes
  10. 10Mathematical models
    1. 10.1 Laplace transforms
    2. 10.2 Transfer function
    3. 10.3 Transient response
    4. 10.4 Frequency response
    5. 10.5 Z-domain
    6. 10.6 Notes
  11. 11Important Notice

9.2.7 DAC total unadjusted error (TUE)

The Total Unadjusted Error (TUE) is the statistical combination of uncorrelated error sources in the linear region of operation for the DAC. Table 9-1 shows the correlative relationships between the various DAC errors that are defined in this chapter.

Table 9-1 DAC error correlation.
Error Offset Gain Zero-Code Full-Scale DNL INL
Offset - - Correlated Correlated - -
Gain - - - Correlated - -
Zero-Code Correlated - - - - -
Full-Scale Correlated Correlated - - Correlated Correlated
DNL - - - Correlated - Correlated
INL - - - Correlated Correlated -

The TUE equation is shown below, where all error sources must first be normalized to a common unit format (such as LSBs or parts per million). Table 9-2 shows the calculations required to convert between different unit formats.

TUE Equation

Equation 91. TUE = E Offset 2 + E Gain 2 + E INL 2
Where

EOffset = The static component of output error across the transfer function. See DAC Offset Error.

EGain = The proportionate component of output error across the transfer function. See DAC Gain Error.

EINL = The maximum deviation of the output from a straight-line fit of the transfer function. See DAC INL.

Table 9-2 Unit conversions for error.
Convert To
Codes Volts % ppm
From Codes - Codes • V FSR 2 n Codes • 100 2 n Codes • 10 6 2 n
Volts Volts • 2 n V FSR - Volts • 100 V FSR Volts • 10 6 V FSR
% % • 2 n 100 % • V FSR 100 - % • 10 6 100
ppm ppm • 2 n 10 6 ppm • V FSR 10 6 ppm • 100 10 6 -

A single TUE calculation can be useful for comparing the relative performance between different DACs, but it may not produce accurate estimates of typical error in the system. For example, the TUE equation treats EGain as a uniform contributor of error across the transfer function, but EGain is actually a scaled error with minimal influence on the lower codes. An improved estimate of system error may be produced by breaking up the transfer function into multiple regions, where the error components are adjusted in the TUE calculation based on their expected contribution to each region.