SLWS214C October   2008  – May 2026 ADS61B29 , ADS61B49

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1. 4.1 Pin Configuration and Functions (LVDS Mode) — ADS61B49 and ADS61B29
    2. 4.2 Pin Configuration and Functions (CMOS Mode) – ADS61B49 and ADS61B29
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  Recommended Operating Conditions
    3. 5.3  Electrical Characteristics – ADS61B49 and ADS61B29
    4. 5.4  Electrical Characteristics – ADS61B49 and ADS61B29
    5. 5.5  Electrical Characteristics – ADS61B49 and ADS61B29
    6. 5.6  Digital Characteristics – ADS61B49 and ADS61B29
    7. 5.7  Timing Requirements – LVDS and CMOS Modes
    8. 5.8  Typical Characteristics - ADS61B49
    9. 5.9  Typical Characteristics - ADS61B29
    10. 5.10 Typical Characteristics - Common Plots (both ADS61B49/61B29)
    11. 5.11 Contour Plots - ADS61B49/ADS61B29
    12. 5.12 Contour Plots - ADS61B49
    13. 5.13 Contour Plots - ADS61B29
  7. 6 Detailed Description
    1. 6.1 Functional Block Diagrams
      1. 6.1.1 ADS61B29 Block Diagram
      2. 6.1.2 ADS61B49 Block Diagram
    2. 6.2 Feature Description
      1. 6.2.1 Device Configuration
      2. 6.2.2 Parallel Configuration Only
      3. 6.2.3 Serial Interface Configuration Only
      4. 6.2.4 Configuration Using Both The Serial Interface and Parallel Controls
      5. 6.2.5 Description of Parallel Pins
      6. 6.2.6 Serial Interface
        1. 6.2.6.1 Register Initialization
      7. 6.2.7 Serial Interface Timing Characteristics
      8. 6.2.8 Serial Register Readout
      9. 6.2.9 Reset Timing
    3. 6.3 Serial Register Map
      1. 6.3.1 Description of Serial Registers
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1  Theory of Operation
      2. 7.1.2  Analog Input
        1. 7.1.2.1 Drive Circuit Requirements
        2. 7.1.2.2 Driving Circuit
        3. 7.1.2.3 Input Common-Mode
      3. 7.1.3  Reference
      4. 7.1.4  Clock Input
      5. 7.1.5  Fine Gain Control
      6. 7.1.6  Offset Correction
      7. 7.1.7  Power Down
        1. 7.1.7.1 Power-Down Global
        2. 7.1.7.2 Standby
        3. 7.1.7.3 Output Buffer Disable
        4. 7.1.7.4 Input Clock Stop
      8. 7.1.8  Power Supply Sequence
      9. 7.1.9  Digital Output Information
        1. 7.1.9.1 Output Interface
        2. 7.1.9.2 DDR LVDS Outputs
        3. 7.1.9.3 LVDS Buffer
        4. 7.1.9.4 Parallel CMOS Interface
        5. 7.1.9.5 Output Buffer Strength Programmability
        6. 7.1.9.6 CMOS Interface Power Dissipation
        7. 7.1.9.7 Output Data Format
      10. 7.1.10 Board Design Considerations
        1. 7.1.10.1 Grounding
        2. 7.1.10.2 Supply Decoupling
        3. 7.1.10.3 Exposed Pad
      11. 7.1.11 Definition of Specifications
  9. 8 Device and Documentation Support
    1. 8.1 Third-Party Products Disclaimer
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

7.1.1 Theory of Operation

The ADS61B49/29 are high performance, low power 14-bit and 12-bit A/D converters with maximum sampling rates up to 250 MSPS. The primary difference from the ADS6149/29 is the addition of an integrated analog buffer (hence B in the device name).

The conversion process is initiated by a rising edge of the external input clock and the analog input signal is sampled. The sampled signal is sequentially converted by a series of small resolution stages, with the outputs combined in a digital correction logic block. At every clock edge the sample propagates through the pipeline resulting in a data latency of 18 clock cycles. The output is available as 14-bit/12-bit data, in DDR LVDS or CMOS and coded in either straight offset binary or binary 2s complement format.

The dynamic offset of the first stage sub-ADC limits the maximum analog input frequency to about 500MHz (with 2-Vpp amplitude) and about 800MHz (with 1-Vpp amplitude) before the performance becomes ill-behaved. This is separate from the full power analog bandwidth of 750MHz, which is only an indicator of signal amplitude versus frequency.