SBAS821 December   2017 ADS7057

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Digital Voltage Levels
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Product Family
      2. 8.3.2 Analog Input
      3. 8.3.3 Reference
      4. 8.3.4 ADC Transfer Function
    4. 8.4 Device Functional Modes
      1. 8.4.1 ACQ State
      2. 8.4.2 CNV State
      3. 8.4.3 OFFCAL State
        1. 8.4.3.1 Offset Calibration on Power-Up
        2. 8.4.3.2 Offset Calibration During Normal Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 2-Channel, Simultaneous Sampling Data Acquisition Using the ADS7057
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Low Distortion Charge Kickback Filter Design
          2. 9.2.1.2.2 Input Amplifier Selection
          3. 9.2.1.2.3 Reference Circuit
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Improving Precision of Single-Ended Signal Source Measurements Using the ADS7057
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curve
  10. 10Power Supply Recommendations
    1. 10.1 AVDD and DVDD Supply Recommendations
    2. 10.2 Optimizing Power Consumed by the Device
      1. 10.2.1 Estimating Digital Power Consumption
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

11 Layout

11.1 Layout Guidelines

Figure 47 shows a typical connection diagram for the ADS7057.

ADS7057 layout_sch_diff_sbas769.gif Figure 47. Typical Connection Diagram

Figure 48 depicts a board layout example for the device for the typical connection diagram in Figure 47. The key considerations for layout are:

  • Use a solid ground plane underneath the device and partition the PCB into analog and digital sections
  • Avoid crossing digital lines with the analog signal path and keep the analog input signals and the reference input signals away from noise sources.
  • The power sources to the device must be clean and well-bypassed. Use CAVDD decoupling capacitors in close proximity to the analog (AVDD) power-supply pin.
  • Use a CDVDD decoupling capacitor close to the digital (DVDD) power-supply pin.
  • Avoid placing vias between the AVDD and DVDD pins and the bypass capacitors.
  • Connect the ground pin to the ground plane using a short, low-impedance path.
  • Place the charge kickback filter components close to the device.

Among ceramic surface-mount capacitors, COG (NPO) ceramic capacitors are recommended because these components provide the most stable electrical properties over voltage, frequency, and temperature changes.

11.2 Layout Example

ADS7057 layout_layout_diff_sbas769.gif Figure 48. Example Layout