SBASAZ0 August   2024 AMC0136

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information (DEN Package)
    5. 5.5 Package Characteristics
    6. 5.6 Electrical Characteristics
    7. 5.7 Switching Characteristics
    8. 5.8 Timing Diagram
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Analog Input
      2. 6.3.2 Modulator
      3. 6.3.3 Isolation Channel Signal Transmission
      4. 6.3.4 Digital Output
        1. 6.3.4.1 Output Behavior in Case of a Full-Scale Input
        2. 6.3.4.2 Output Behavior in Case of a Missing High-Side Supply
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Input Filter Design
      4. 7.2.4 Bitstream Filtering
    3. 7.3 Best Design Practices
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Mechanical Data

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.2.4 Bitstream Filtering

The modulator generates a bitstream that is processed by a digital filter to obtain a digital word similar to a conversion result of a conventional analog-to-digital converter (ADC). Equation 2 shows a sinc3-type filter, which is a very simple filter built with minimal effort and hardware.

 

Equation 2. AMC0136

This filter provides the best output performance at the lowest hardware size (count of digital gates) for a second-order modulator. All characterization in this document is also done with a sinc3 filter with an oversampling ratio (OSR) of 256 and a 16-bit output word width.

The Combining the ADS1202 with an FPGA Digital Filter for Current Measurement in Motor Control Applications application note discusses an example code. Use this example code for implementing a sinc3 filter in an FPGA. This application note is available for download at www.ti.com.

For modulator output bitstream filtering, use a device from TI's C2000 or Sitara microcontroller families. These families support multichannel dedicated hardwired filter structures that significantly simplify system level design by offering two filtering paths per channel. One path provides high-accuracy results for the control loop and the other provides a fast-response path for overcurrent detection.

A delta sigma modulator filter calculator is available for download at www.ti.com that aids in the filter design and correct OSR and filter order selection. This calculator helps achieve the desired output resolution and filter response time.