SBAS587A January   2014  – April 2014 ADS7251 , ADS7851

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Terminal Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  Handling Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics: ADS7251
    6. 6.6  Electrical Characteristics: ADS7851
    7. 6.7  Electrical Characteristics: Common
    8. 6.8  ADS7251 Timing Characteristics
    9. 6.9  ADS7851 Timing Characteristics
    10. 6.10 Typical Characteristics: ADS7251
    11. 6.11 Typical Characteristics: ADS7851
    12. 6.12 Typical Characteristics: Common
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Reference
      2. 7.3.2 Analog Input
        1. 7.3.2.1 Analog Input Full-Scale Range
        2. 7.3.2.2 Common-Mode Voltage Range
      3. 7.3.3 ADC Transfer Function
    4. 7.4 Device Functional Modes
      1. 7.4.1 Serial Interface
      2. 7.4.2 Short-Cycling Feature
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Amplifier Selection
        2. 8.2.2.2 Antialiasing Filter
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9 Power Supply Recommendations

The devices have two separate power supplies: AVDD and DVDD. The device operates on AVDD; DVDD is used for the interface circuits. AVDD and DVDD can be independently set to any value within the permissible ranges.

The AVDD supply voltage value defines the permissible voltage swing on the analog input pins. To avoid saturation of output codes, and to use the full dynamic range on the analog input pins, AVDD must be set as shown in Equation 12, Equation 13, and Equation 14:

Equation 12. AVDD ≥ 2 × VREF_A
Equation 13. AVDD ≥ 2 × VREF_B
Equation 14. 4.75 V ≤ AVDD ≤ 5.25 V

Decouple the AVDD and DVDD pins with the GND pin using individual 10-µF decoupling capacitors, as shown in Figure 51.

ai_supply_bas580.gifFigure 51. Power-Supply Decoupling