SBAS543C August   2011  – February 2016 ADS8528 , ADS8548 , ADS8568

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics: General
    6. 7.6  Electrical Characteristics: ADS8528
    7. 7.7  Electrical Characteristics: ADS8548
    8. 7.8  Electrical Characteristics: ADS8568
    9. 7.9  Serial Interface Timing Requirements
    10. 7.10 Parallel Interface Timing Requirements (Read Access)
    11. 7.11 Parallel Interface Timing Requirements (Write Access)
    12. 7.12 Typical Characteristics
  8. 8 Parameter Measurement information
    1. 8.1 Equivalent Circuits
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Analog
        1. 9.3.1.1 Analog Inputs
        2. 9.3.1.2 Analog-to-Digital Converter (ADC)
        3. 9.3.1.3 Conversion Clock
        4. 9.3.1.4 CONVST_x
        5. 9.3.1.5 Data Readout and BUSY/INT Signal
        6. 9.3.1.6 Sequential Operation
        7. 9.3.1.7 Reference
      2. 9.3.2 Digital
        1. 9.3.2.1 Device Configuration
        2. 9.3.2.2 Parallel Interface
        3. 9.3.2.3 Serial Interface
        4. 9.3.2.4 Output Data Format
    4. 9.4 Device Functional Modes
      1. 9.4.1 Hardware Mode
      2. 9.4.2 Software Mode
      3. 9.4.3 Daisy-Chain Mode
      4. 9.4.4 Reset and Power-Down Modes
    5. 9.5 Register Maps
      1. 9.5.1 Configuration (CONFIG) Register
        1. 9.5.1.1 CONFIG: Configuration Register (default = 000003FFh)
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Related Links
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

12 Layout

12.1 Layout Guidelines

All ground pins must be connected to a clean ground reference. Keep this connection as short as possible to minimize the inductance of these paths. Using vias is recommended to connect the pads directly to the corresponding ground plane. In designs without ground planes, keep the ground trace as wide and as short as possible to reduce inductance. Avoid connections that are too close to the grounding point of a microcontroller or digital signal processor.

Depending on the circuit density on the board, placement of the analog and digital components, and the related current loops, a single solid ground plane for the entire printed circuit board (PCB) or dedicated analog and digital ground areas can be used. In case of separated ground areas, ensure that a low-impedance connection is between the analog and digital ground of the ADC by placing a bridge underneath (or next to) the ADC. Otherwise, even short undershoots on the digital interface with a value less than –300 mV lead to the conduction of ESD diodes, causing current to flow through the substrate and either degrading the analog performance or even damaging the device. Using a common ground plane underneath the device is recommended as a local ground reference for all xGND pins; see Figure 49. During PCB layout, care must be taken to avoid any return currents crossing sensitive analog areas or signals.

12.2 Layout Example

Figure 49 shows a layout recommendation for the ADS85x8 along with the proper decoupling and reference capacitors placement and connections. The layout recommendation takes into account the actual size of the components used.

ADS8528 ADS8548 ADS8568 ai_layout_bas543.gif
1. All AVDD and DVDD decoupling capacitors are placed on the bottom layer underneath the device power-supply pins and are connected by vias. All 100-nF ceramic capacitors are placed as close as possible to the device and the 10-µF capacitors are also placed close but without compromising the placement of the smaller capacitors.
Figure 49. Layout Recommendation