SPRACZ9A November   2021  – December 2022 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

 

  1.   Hardware Design Guide for F2800x Devices
  2.   Trademarks
  3. 1Introduction
  4. 2Typical F2800x System Block Diagram
  5. 3Schematic Design
    1. 3.1 Package and Device Decision
      1. 3.1.1 F2800x Devices
        1. 3.1.1.1 TMS320F28004x
        2. 3.1.1.2 TMS320F28002x
        3. 3.1.1.3 TMS320F28003x
        4. 3.1.1.4 TMS320F280013x
      2. 3.1.2 Migration Guides
      3. 3.1.3 PinMux Tool
      4. 3.1.4 Configurable Logic Block
    2. 3.2 Digital IOs
      1. 3.2.1 General Purpose Input/Outputs
      2. 3.2.2 Integrated Peripherals and X-BARs
      3. 3.2.3 Control Peripherals
      4. 3.2.4 Communication Peripherals
      5. 3.2.5 Boot Pins and Boot Peripherals
    3. 3.3 Analog IOs
      1. 3.3.1 Analog Peripherals
      2. 3.3.2 Choosing Analog Pins
      3. 3.3.3 Internal vs. External Analog Reference
      4. 3.3.4 ADC Inputs
      5. 3.3.5 Driving Options
      6. 3.3.6 Low-Pass/Anti-Aliasing Filters
    4. 3.4 Power Supply
      1. 3.4.1 Power Requirements
      2. 3.4.2 Power Sequencing
      3. 3.4.3 VDD Voltage Regulator
        1. 3.4.3.1 Internal vs. External Regulator
        2. 3.4.3.2 Internal LDO vs. Internal DC-DC Regulator
      4. 3.4.4 Power Consumption
      5. 3.4.5 Power Calculations
    5. 3.5 XRSn and System Reset
    6. 3.6 Clocking
      1. 3.6.1 Internal vs. External Oscillator
    7. 3.7 Debugging and Emulation
      1. 3.7.1 JTAG/cJTAG
      2. 3.7.2 Debug Probe
    8. 3.8 Unused Pins
  6. 4PCB Layout Design
    1. 4.1 Layout Design Overview
      1. 4.1.1 Recommend Layout Practices
      2. 4.1.2 Board Dimensions
      3. 4.1.3 Layer Stack-Up
    2. 4.2 Recommended Board Layout
    3. 4.3 Placing Components
      1. 4.3.1 Power Electronic Considerations
    4. 4.4 Ground Plane
    5. 4.5 Analog and Digital Separation
    6. 4.6 Signal Routing With Traces and Vias
    7. 4.7 Thermal Considerations
  7. 5EOS, EMI/EMC, and ESD Considerations
    1. 5.1 Electrical Overstress
    2. 5.2 Electromagnetic Interference and Electromagnetic Compatibility
    3. 5.3 Electrostatic Discharge
  8. 6Final Details and Checklist
  9. 7References
  10. 8Revision History

3.3.4 ADC Inputs

The ADCs should be properly designed and evaluated to ensure proper performance. The analog-to-digital converters have input impedance and bandwidth requirements which could lead to memory cross-talk and significant sample-and-hold (S+H) circuit settling errors.

The diagram below outlines the ADC Input Model, where Cp describes the parasitic input capacitance, Ron describes the sampling switch resistance, Ch describes the sampling capacitor, and Rs describes the nominal source impedance. The data sheet documents the ADC per-channel parasitic capacitances that can help in deciding which ADCs to use. Note that the acquisition window duration can be adjusted for each SOC by adjusting ACQPS or lowering the sampling frequency, or a combination of both. To evaluating the driving circuit, simulate it in TINA-TI to ensure correct performance and settling.

Figure 3-8 ADC Input Model

For a deeper dive into this topic, see the ADC Input Circuit Evaluation for C2000 MCUs. Additionally, to improve the ADC performance and reduce memory cross-talk, see the Methods for Mitigating ADC Memory Cross-Talk.