SBAS888B December   2020  – July 2022 ADC3664

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 - Power Consumption
    6. 6.6 Electrical Characteristics - DC Specifications
    7. 6.7 Electrical Characteristics - AC Specifications
    8. 6.8 Timing Requirements
    9. 6.9 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input
        1. 8.3.1.1 Analog Input Bandwidth
        2. 8.3.1.2 Analog Front End Design
          1. 8.3.1.2.1 Sampling Glitch Filter Design
          2. 8.3.1.2.2 Analog Input Termination and DC Bias
            1. 8.3.1.2.2.1 AC-Coupling
            2. 8.3.1.2.2.2 DC-Coupling
      2. 8.3.2 Clock Input
        1. 8.3.2.1 Single Ended vs Differential Clock Input
      3. 8.3.3 Voltage Reference
        1. 8.3.3.1 Internal voltage reference
        2. 8.3.3.2 External voltage reference (VREF)
        3. 8.3.3.3 External voltage reference with internal buffer (REFBUF)
      4. 8.3.4 Digital Down Converter
        1. 8.3.4.1 DDC MUX
        2. 8.3.4.2 Digital Filter Operation
        3. 8.3.4.3 FS/4 Mixing with Real Output
        4. 8.3.4.4 Numerically Controlled Oscillator (NCO) and Digital Mixer
        5. 8.3.4.5 Decimation Filter
        6. 8.3.4.6 SYNC
        7. 8.3.4.7 Output Formatting with Decimation
      5. 8.3.5 Digital Interface
        1. 8.3.5.1 Output Formatter
        2. 8.3.5.2 Output Bit Mapper
        3. 8.3.5.3 Output Interface/Mode Configuration
          1. 8.3.5.3.1 Configuration Example
        4. 8.3.5.4 Output Data Format
      6. 8.3.6 Test Pattern
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal operation
      2. 8.4.2 Power Down Options
    5. 8.5 Programming
      1. 8.5.1 Configuration using PINs only
      2. 8.5.2 Configuration using the SPI interface
        1. 8.5.2.1 Register Write
        2. 8.5.2.2 Register Read
    6. 8.6 Register Maps
      1. 8.6.1 Detailed Register Description
  9. 9 Application Information Disclaimer
    1. 9.1 Typical Application
      1. 9.1.1 Design Requirements
      2. 9.1.2 Detailed Design Procedure
        1. 9.1.2.1 Input Signal Path
        2. 9.1.2.2 Sampling Clock
        3. 9.1.2.3 Voltage Reference
      3. 9.1.3 Application Curves
    2. 9.2 Initialization Set Up
      1. 9.2.1 Register Initialization During Operation
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

8.3.5.1 Output Formatter

The digital output interface utilizes a flexible output bit mapper (Figure 8-34). The bit mapper takes the 14-bit output directly from the ADC or from digital filter block and reformats it to a resolution of 14, 16, 18 or 20-bit. The output serialization factor gets adjusted accordingly for 2-, 1- and 1/2-wire interface mode. The maximum output data rate can not be exceeded independently of output resolution and serialization factor.

When using 16-bit or higher output resolution in non-decimation mode, the 2 LSBs are set to 0.

Figure 8-34 Interface output bit mapper

Table 8-5 provides an overview for the resulting serialization factor depending on output resolution and output modes. Note that the DCLKIN frequency needs to be adjusted accordingly as well. Changing the output resolution to 16-bit, 2-wire mode for example would result in DCLKIN = FS * 4 instead of * 3.5.

The output bit mapper can be used for bypass and decimation filter.

Table 8-5 Serialization factor vs output resolution for different output modes
OUTPUT RESOLUTIONInterfaceSERIALIZATIONFCLKDCLKINDCLKD0/D1
14-bit (default)2-Wire7xFS/2FS* 3.5FS* 3.5FS* 7
1-Wire14xFSFS* 7FS* 7FS* 14
1/2-Wire28xFSFS* 14FS* 14FS* 28
16-bit2-Wire8xFS/2FS* 4FS* 4FS* 8
1-Wire16xFSFS* 8FS* 8FS* 16
1/2-Wire32xFSFS* 16FS* 16FS* 32
18-bit2-Wire9xFS/2FS* 4.5FS* 4.5FS* 9
1-Wire18xFSFS* 9FS* 9FS* 18
1/2-Wire36xFSFS* 18FS* 18FS* 36
20-bit2-Wire10xFS/2FS* 5FS* 5FS* 10
1-Wire20xFSFS* 10FS* 10FS* 20
1/2-Wire40xFSFS* 20FS* 20FS* 40

The programming sequence to change the output interface and/or resolution from default settings is shown in Output Interface/Mode Configuration.