SBAS872B December   2020  – October 2022 ADC3681 , ADC3682 , ADC3683

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 - ADC3681
    10. 6.10 Typical Characteristics - ADC3682
    11. 6.11 Typical Characteristics - ADC3683
  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
        3. 8.3.1.3 Auto-Zero Feature
      2. 8.3.2 Clock Input
        1. 8.3.2.1 Single Ended vs Differential Clock Input
        2. 8.3.2.2 Signal Acquisition Time Adjust
      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 Scrambler
        3. 8.3.5.3 Output Bit Mapper
        4. 8.3.5.4 Output Interface/Mode Configuration
          1. 8.3.5.4.1 Configuration Example
        5. 8.3.5.5 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
      3. 8.4.3 Digital Channel Averaging
    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 Map
      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

Package Options

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

8.3.5.4 Output Interface/Mode Configuration

The following sequence summarizes all the relevant registers for changing the output interface and/or enabling the decimation filter. Steps 1 and 2 must come first since the E-Fuse load reset the SPI writes, the remaining steps can come in any order.

Table 8-8 Configuration steps for changing interface or decimation
STEPFEATUREADDRESSDESCRIPTION
1Output Interface0x07Select the output interface bit mapping depending on resolution and output interface.
Output Resolution2-wire1-wire1/2-wire
14-bit0x2B0x6C0x8D
16-bit0x4B
18-bit0x2B
20-bit0x4B
20x13Load the output interface bit mapping using the E-fuse loader (0x13, D0). Program register 0x13 to 0x01, wait ~ 1ms so that bit mapping is loaded properly followed by 0x13 0x00
30x19Configure the FCLK frequency based on bypass/decimation and number of lanes used.
Bypass/DecSLVDSFCLK SRC
(D7)		FCLK DIV
(D4)		TOG FCLK
(D0)
Bypass/ Real Decimation2-wire010
1-wire000
1/2-wire000
Complex Decimation2-wire100
1-wire100
1/2-wire001
40x1BSelect the output interface resolution using the bit mapper (D5-D3).
50x20
0x21
0x22		Select the FCLK pattern for decimation for proper duty cycle output of the frame clock.
Output Resolution2-wire1-wire1/2-wire
Real Decimation14-bituse default0xFE000use default
16-bit0xFF000
18-bit0xFF800
20-bit 0xFFC00
Complex Decimation14-bit0xFFFFF0xFFFFF
16-bit
18-bit
20-bit
6 0x39..0x60
0x61..0x88		 Change output bit mapping for chA and chB if desired. This works also with the default interface selection.
7 0x24
0x22		 Enable scrambling
8Decimation Filter0x24Enable the decimation filter
90x25Configure the decimation filter
100x2A/B/C/D
0x31/2/3/4		Program the NCO frequency for complex decimation (can be skipped for real decimation)
110x27
0x2E		Configure the complex output data stream (set both bits to 0 for real decimation)
SLVDSOP-Order (D4)Q-Delay (D3)
2-wire10
1-wire01
1/2-wire11
120x26Set the mixer gain and toggle the mixer reset bit to update the NCO frequency.