SBAS653B April   2014  – October 2020 ADS4245-EP

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  Electrical Characteristics: General
    7. 6.7  Digital Characteristics
    8. 6.8  Timing Characteristics: LVDS And CMOS Modes
    9. 6.9  Typical Characteristics:
    10. 6.10 Typical Characteristics: General
    11. 6.11 Typical Characteristics: Contour
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Digital Functions
      2. 7.4.2 Gain For SFDR/SNR Trade-Off
      3. 7.4.3 Offset Correction
      4. 7.4.4 Power-Down
        1. 7.4.4.1 Global Power-Down
        2. 7.4.4.2 Channel Standby
        3. 7.4.4.3 Input Clock Stop
      5. 7.4.5 Digital Output Information
        1. 7.4.5.1 Output Interface
        2. 7.4.5.2 DDR LVDS Outputs
        3. 7.4.5.3 LVDS Buffer
        4. 7.4.5.4 Parallel CMOS Interface
        5. 7.4.5.5 CMOS Interface Power Dissipation
        6. 7.4.5.6 Multiplexed Mode Of Operation
        7. 7.4.5.7 Output Data Format
      6. 7.4.6 Device Configuration
        1. 7.4.6.1 Parallel Configuration Only
        2. 7.4.6.2 Serial Interface Configuration Only
        3. 7.4.6.3 Using Both Serial Interface And Parallel Controls
        4. 7.4.6.4 Parallel Configuration Details
        5. 7.4.6.5 Serial Interface Details
          1. 7.4.6.5.1 Register Initialization
          2. 7.4.6.5.2 Serial Register Readout
    5. 7.5 Serial Register Map
    6. 7.6 Description Of Serial Registers
  8. 8 Application Information Disclaimer
    1. 8.1 Application Information
      1. 8.1.1 Clock Input
    2. 8.2 Typical Applications
      1. 8.2.1 Analog Input
        1. 8.2.1.1 Design Requirements for Drive Circuits
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Grounding
      2. 10.1.2 Supply Decoupling
      3. 10.1.3 Exposed Pad
      4. 10.1.4 Routing Analog Inputs
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Support
        1. 11.1.1.1 Definition Of Specifications
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.4.2 Gain For SFDR/SNR Trade-Off

The ADS4245 includes gain settings that can be used to get improved SFDR performance (compared to no gain). The gain is programmable from 0dB to 6dB (in 0.5dB steps). For each gain setting, the analog input full-scale range scales proportionally, as shown in Table 7-2.

The SFDR improvement is achieved at the expense of SNR; for each gain setting, the SNR degrades approximately between 0.5dB and 1dB. The SNR degradation is reduced at high input frequencies. As a result, the gain is very useful at high input frequencies because the SFDR improvement is significant with marginal degradation in SNR. Therefore, the gain can be used as a trade-off between SFDR and SNR. Note that the default gain after reset is 0dB.

Table 7-2 Full-Scale Range Across Gains
GAIN (dB)TYPEFULL-SCALE (VPP)
0Default after reset2
1Fine, programmable1.78
2Fine, programmable1.59
3Fine, programmable1.42
4Fine, programmable1.26
5Fine, programmable1.12
6Fine, programmable1