SBAS569B May   2013  – February 2019 ADS8860

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      No Separate LDO Required for the ADC Supply
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin 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
    6. 7.6 Timing Requirements: 3-Wire Operation
    7. 7.7 Timing Requirements: 4-Wire Operation
    8. 7.8 Timing Requirements: Daisy-Chain
    9. 7.9 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 Input
      2. 9.3.2 Reference
      3. 9.3.3 Clock
      4. 9.3.4 ADC Transfer Function
    4. 9.4 Device Functional Modes
      1. 9.4.1 CS Mode
        1. 9.4.1.1 3-Wire CS Mode Without a Busy Indicator
        2. 9.4.1.2 3-Wire CS Mode With a Busy Indicator
        3. 9.4.1.3 4-Wire CS Mode Without a Busy Indicator
        4. 9.4.1.4 4-Wire CS Mode With a Busy Indicator
      2. 9.4.2 Daisy-Chain Mode
        1. 9.4.2.1 Daisy-Chain Mode Without a Busy Indicator
        2. 9.4.2.2 Daisy-Chain Mode With a Busy Indicator
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 ADC Reference Driver
      2. 10.1.2 ADC Input Driver
        1. 10.1.2.1 Input Amplifier Selection
        2. 10.1.2.2 Charge-Kickback Filter
    2. 10.2 Typical Applications
      1. 10.2.1 DAQ Circuit for a 1-µs, Full-Scale Step Response
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
      2. 10.2.2 DAQ Circuit for Lowest Distortion and Noise Performance at 1 MSPS
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
      3. 10.2.3 Ultralow-Power DAQ Circuit at 10 kSPS
        1. 10.2.3.1 Design Requirements
        2. 10.2.3.2 Detailed Design Procedure
  11. 11Power Supply Recommendations
    1. 11.1 Power-Supply Decoupling
    2. 11.2 Power Saving
  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 Receiving Notification of Documentation Updates
    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

9.3.1 Analog Input

As shown in Figure 44, the device features a single-ended analog input. AINP can swing from GND – 0.1 V to VREF + 0.1 V and AINN can swing from GND – 0.1 V to GND + 0.1 V. Both positive and negative inputs are individually sampled on 55-pF sampling capacitors and the device converts for the voltage difference between the two sampled values: VINP – VINN. The single-ended signal range is 0 V to VREF.

Figure 45 shows an equivalent circuit of the input sampling stage. The sampling switch is represented by a 96-Ω resistance in series with the ideal switch; see the ADC Input Driver section for more details on the recommended driving circuits.

ADS8860 ai_input_sample_equiv_bas557.gifFigure 45. Input Sampling Stage Equivalent Circuit

Figure 44 and Figure 45 illustrate electrostatic discharge (ESD) protection diodes to REF and GND from both analog inputs. Make sure that these diodes do not turn on by keeping the analog inputs within the specified range.