SBAS533E March   2011  – February 2023 ADS4222 , ADS4225 , ADS4226 , ADS4242 , ADS4245 , ADS4246

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions – LVDS Mode
    2.     Pin Functions – CMOS Mode
  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: ADS4246, ADS4245, ADS4242
    6. 7.6  Electrical Characteristics: ADS4226, ADS4225, ADS4222
    7. 7.7  Electrical Characteristics: General
    8. 7.8  Digital Characteristics
    9. 7.9  Timing Requirements: LVDS and CMOS Modes (1)
    10. 7.10 Serial Interface Timing Characteristics (1)
    11. 7.11 Reset Timing (Only When Serial Interface Is Used)
    12. 7.12 Typical Characteristics
      1. 7.12.1 ADS4246
      2. 7.12.2 ADS4245
      3. 7.12.3 ADS4242
      4. 7.12.4 ADS4226
      5. 7.12.5 ADS4225
      6. 7.12.6 ADS4222
      7. 7.12.7 General
      8. 7.12.8 Contour
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input
        1. 8.3.1.1 Drive Circuit Requirements
        2. 8.3.1.2 Driving Circuit
      2. 8.3.2 Clock Input
      3. 8.3.3 Digital Functions
      4. 8.3.4 Gain for SFDR/SNR Trade-off
      5. 8.3.5 Offset Correction
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Down
        1. 8.4.1.1 Global Power-Down
        2. 8.4.1.2 Channel Standby
        3. 8.4.1.3 Input Clock Stop
    5. 8.5 Programming
      1. 8.5.1 47
      2. 8.5.2 Parallel Configuration Only
      3. 8.5.3 Serial Interface Configuration Only
      4. 8.5.4 Using Both Serial Interface and Parallel Controls
      5. 8.5.5 Parallel Configuration Details
      6. 8.5.6 Serial Interface Details
        1. 8.5.6.1 Register Initialization
        2. 8.5.6.2 Serial Register Readout
      7. 8.5.7 Digital Output Information
        1. 8.5.7.1 Output Interface
        2. 8.5.7.2 DDR LVDS Outputs
        3. 8.5.7.3 LVDS Buffer
        4. 8.5.7.4 Parallel CMOS Interface
        5. 8.5.7.5 CMOS Interface Power Dissipation
        6. 8.5.7.6 Multiplexed Mode of Operation
        7. 8.5.7.7 Output Data Format
    6. 8.6 Register Maps
      1. 8.6.1 64
      2. 8.6.2 Description Of Serial Registers
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Analog Input
        2. 9.2.2.2 Clock Driver
        3. 9.2.2.3 Digital Interface
        4. 9.2.2.4 SNR and Clock Jitter
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Sharing DRVDD and AVDD Supplies
      2. 9.3.2 Using DC/DC Power Supplies
      3. 9.3.3 Power Supply Bypassing
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Grounding
        2. 9.4.1.2 Supply Decoupling
        3. 9.4.1.3 Exposed Pad
        4. 9.4.1.4 Routing Analog Inputs
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Device Nomenclature
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.5 Offset Correction

The ADS424x/422x have an internal offset correction algorithm that estimates and corrects dc offset up to ±10 mV. The correction can be enabled using the ENABLE OFFSET CORR serial register bit. Once enabled, the algorithm estimates the channel offset and applies the correction every clock cycle. The time constant of the correction loop is a function of the sampling clock frequency. The time constant can be controlled using the OFFSET CORR TIME CONSTANT register bits, as described in #GUID-2F140A1C-A630-4850-912B-840410130B61/SBAS4831377.

After the offset is estimated, the correction can be frozen by setting FREEZE OFFSET CORR = 0. Once frozen, the last estimated value is used for the offset correction of every clock cycle. Note that offset correction is disabled by default after reset.

Table 8-3 Time Constant of Offset Correction Algorithm
OFFSET CORR TIME CONSTANTTIME CONSTANT, TCCLK
(Number of Clock Cycles)		TIME CONSTANT, TCCLK × 1/fS (ms)(1)
00001M7
00012M13
00104M26
00118M52
010016M105
010132M210
011064M419
0111128M839
1000256M1678
1001512M3355
10101G6711
10112G13422
1100Reserved—
1101Reserved—
1110Reserved—
1111Reserved—
(1) Sampling frequency, fS = 160 MSPS.