SLASE60B September   2015  – January 2019 ADC31JB68

PRODUCTION DATA.  

  1. Features
    1.     Transmitted Eye at Output of 18-Inch, 5-mil. FR4 Microstrip Trace at 5 Gb/s With Optimized De-Emphasis
  2. Applications
  3. Description
    1.     Spectrum With –1-dBFS, 450-MHz Input
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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: Converter Performance
    6. 6.6 Electrical Characteristics: Power Supply
    7. 6.7 Electrical Characteristics: Interface
    8. 6.8 Timing Requirements
    9. 6.9 Typical Characteristics
  7. Parameter Measurement Information
    1. 7.1 Interface Circuits
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Analog Inputs and Input Buffer
      2. 8.3.2  Amplitude and Phase Imbalance Correction
      3. 8.3.3  Over-Range Detection
      4. 8.3.4  Input Clock Divider
      5. 8.3.5  SYSREF Detection Gate
      6. 8.3.6  Serial Differential Output Drivers
        1. 8.3.6.1 De-Emphasis Equalization
        2. 8.3.6.2 Serial Lane Inversion
      7. 8.3.7  ADC Core Calibration
      8. 8.3.8  Data Format
      9. 8.3.9  JESD204B Supported Features
      10. 8.3.10 JESD204B Interface
      11. 8.3.11 Transport Layer Configuration
        1. 8.3.11.1 Lane Configuration
        2. 8.3.11.2 Frame Format
        3. 8.3.11.3 ILA Information
      12. 8.3.12 Test Pattern Sequences
      13. 8.3.13 JESD204B Link Initialization
        1. 8.3.13.1 Frame Alignment
        2. 8.3.13.2 Code Group Synchronization
      14. 8.3.14 SPI
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Down and Sleep Modes
    5. 8.5 Register Map
      1. 8.5.1 Register Descriptions
        1. 8.5.1.1  CONFIG_A (address = 0x0000) [reset = 0x3C]
          1. Table 6. CONFIG_A
        2. 8.5.1.2  DEVICE CONFIG (address = 0x0002) [reset = 0x00]
          1. Table 7. DEVICE CONFIG
        3. 8.5.1.3  CHIP_TYPE (address = 0x0003 ) [reset = 0x03]
          1. Table 8. CHIP_TYPE
        4. 8.5.1.4  CHIP_ID (address = 0x0005, 0x0004) [reset = 0x00, 0x1B]
          1. Table 9. CHIP_ID
        5. 8.5.1.5  CHIP_VERSION (address =0x0006) [reset = 0x00]
          1. Table 10. CHIP_VERSION
        6. 8.5.1.6  VENDOR_ID (address = 0x000D, 0x000C) [reset = 0x04, 0x51]
          1. Table 11. VENDOR_ID
        7. 8.5.1.7  SPI_CFG (address = 0x0010 ) [reset = 0x01]
          1. Table 12. SPI_CFG
        8. 8.5.1.8  OM1 (Operational Mode 1) (address = 0x0012) [reset = 0xC1]
          1. Table 13. OM1 (Operational Mode 1)
        9. 8.5.1.9  OM2 (Operational Mode 2) (address = 0x0013) [reset = 0x20]
          1. Table 14. OM2 (Operational Mode 2)
        10. 8.5.1.10 IMB_ADJ (Imbalance Adjust) (address = 0x0014) [reset = 0x00]
          1. Table 15. IMB_ADJ (Imbalance Adjust)
        11. 8.5.1.11 OVR_EN (Over-Range Enable) (address = 0x003A) [reset = 0x00]
          1. Table 16. OVR_EN (Over-Range Enable)
        12. 8.5.1.12 OVR_HOLD (Over-Range Hold) (address = 0x003B) [reset = 0x00]
          1. Table 17. OVR_HOLD (Over-Range Hold)
        13. 8.5.1.13 OVR_TH (Over-Range Threshold) (address = 0x003C) [reset = 0x00]
          1. Table 18. OVR_TH (Over-Range Threshold)
        14. 8.5.1.14 DC_MODE (DC Offset Correction Mode) (address = 0x003D) [reset = 0x00]
          1. Table 19. DC_MODE (DC Offset Correction Mode)
        15. 8.5.1.15 SER_CFG (Serial Lane Transmitter Configuration) (address = 0x0047) [reset = 0x00]
          1. Table 20. SER_CFG (Serial Lane Transmitter Configuration)
        16. 8.5.1.16 JESD_CTRL1 (JESD Configuration Control 1) (address = 0x0060) [reset = 0x7F]
          1. Table 21. JESD_CTRL1 (JESD Configuration Control 1)
        17. 8.5.1.17 JESD_CTRL2 (JESD Configuration Control 2) (address = 0x0061) [reset = 0x00]
          1. Table 22. JESD_CTRL2 (JESD Configuration Control 2)
        18. 8.5.1.18 JESD_RSTEP (JESD Ramp Pattern Step) (address = 0x0063, 0x0062) [reset = 0x00, 0x01]
          1. Table 23. JESD_RSTEP (JESD Ramp Pattern Step)
        19. 8.5.1.19 SER_INV (Serial Lane Inversion Control) (address = 0x0064) [reset = 0x00]
          1. Table 24. SER_INV (Serial Lane Inversion Control)
        20. 8.5.1.20 JESD_STATUS (JESD Link Status) (address = 0x006C) [reset = N/A]
          1. Table 25. JESD_STATUS (JESD Link Status)
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Optimizing Converter Performance
        1. 9.1.1.1 Internal Noise Sources
        2. 9.1.1.2 External Noise Sources
      2. 9.1.2 Analog Input Considerations
        1. 9.1.2.1 Differential Analog Inputs and Full Scale Range
        2. 9.1.2.2 Analog Input Network Model
        3. 9.1.2.3 Input Bandwidth
        4. 9.1.2.4 Driving the Analog Input
        5. 9.1.2.5 Clipping and Over-Range
      3. 9.1.3 CLKIN, SYSREF, and SYNCb Input Considerations
        1. 9.1.3.1 Driving the CLKIN+ and CLKIN– Input
        2. 9.1.3.2 Driving the SYSREF Input
        3. 9.1.3.3 SYSREF Signaling
        4. 9.1.3.4 SYSREF Timing
        5. 9.1.3.5 Effectively Using the Detection Gate Feature
        6. 9.1.3.6 Driving the SYNCb Input
      4. 9.1.4 Output Serial Interface Considerations
        1. 9.1.4.1 Output Serial-Lane Interface
        2. 9.1.4.2 Voltage Swing and De-Emphasis Optimization
        3. 9.1.4.3 Minimizing EMI
      5. 9.1.5 JESD204B System Considerations
        1. 9.1.5.1 Frame and LMFC Clock Alignment Procedure
        2. 9.1.5.2 Link Interruption
        3. 9.1.5.3 Clock Configuration Examples
      6. 9.1.6 SPI
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
    1. 10.1 Power Supply Design
    2. 10.2 Decoupling
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Layout Guidelines

The design of the PCB is critical to achieve the full performance of the ADC31JB68 device. Defining the PCB stackup should be the first step in the board design. Experience has shown that at least 6 layers are required to adequately route all required signals to and from the device. Each signal routing layer must have an adjacent solid ground plane to control signal return paths to have minimal loop areas and to achieve controlled impedances for microstrip and stripline routing. Power planes must also have adjacent solid ground planes to control supply return paths. Minimizing the spacing between supply and ground planes improves performance by increasing the distributed decoupling. A recommended stack-up for a 6-layer board design is shown in Figure 80.

Although the ADC31JB68 device consists of both analog and digital circuitry, TI highly recommends solid ground planes that encompass the device and its input and output signal paths. TI does not recommend split ground planes that divide the analog and digital portions of the device. Split ground planes may improve performance if a nearby, noisy, digital device is corrupting the ground reference of the analog signal path. When split ground planes are employed, one must carefully control the supply return paths and keep the paths on top of their respective reference planes.

Quality analog input signal and clock signal path layout is required for full dynamic performance. Symmetry of the differential signal paths and discrete components in the path is mandatory and symmetrical shunt-oriented components should have a common grounding via. The high frequency requirements of the input and clock signal paths necessitate using differential routing with controlled impedances and minimizing signal path stubs (including vias) when possible.

Coupling onto or between the clock and input signal paths must be avoided using any isolation techniques available including distance isolation, orientation planning to prevent field coupling of components like inductors and transformers, and providing well coupled reference planes. Via stitching around the clock signal path and the input analog signal path provides a quiet ground reference for the critical signal paths and reduces noise coupling onto these paths. Sensitive signal traces must not cross other signal traces or power routing on adjacent PCB layers, rather a ground plane should separate the traces. If necessary, the traces should cross at 90° angles to minimize crosstalk.

The substrate dielectric materials of the PCB are largely influenced by the speed and length of the high speed serial lanes. The affordable and common FR4 variety may not offer the consistency or low loss to support the highest speed transmission (5 Gb/s) and long lengths (> 8 inch). Although the VOD and DEM features are available to improve the signal integrity of the serial lanes, some of the highest performing applications may still require special dielectric materials.

Coupling of ambient signals into the signal path is reduced by providing quiet, close reference planes and by maintaining signal path symmetry to ensure the coupled noise is common-mode. Faraday caging may be used in very noisy environments and high dynamic range applications to isolate the signal path.

ADC31JB68 PCB_Stackup.gifFigure 80. Recommended PCB Layer Stack-Up for a Six-Layer Board