SNLS561B February   2017  – October 2019 DS250DF210

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  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
    6. 7.6  Timing Requirements, Retimer Jitter Specifications
    7. 7.7  Timing Requirements, Retimer Specifications
    8. 7.8  Timing Requirements, Recommended Calibration Clock Specifications
    9. 7.9  Recommended SMBus Switching Characteristics (Slave Mode)
    10. 7.10 Recommended SMBus Switching Characteristics (Master Mode)
    11. 7.11 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Device Data Path Operation
      2. 8.3.2  Signal Detect
      3. 8.3.3  Continuous Time Linear Equalizer (CTLE)
      4. 8.3.4  Variable Gain Amplifier (VGA)
      5. 8.3.5  Cross-Point Switch
      6. 8.3.6  Decision Feedback Equalizer (DFE)
      7. 8.3.7  Clock and Data Recovery (CDR)
      8. 8.3.8  Calibration Clock
      9. 8.3.9  Differential Driver With FIR Filter
        1. 8.3.9.1 Setting the Output VOD, Precursor, and Postcursor Equalization
        2. 8.3.9.2 Output Driver Polarity Inversion
      10. 8.3.10 Debug Features
        1. 8.3.10.1 Pattern Generator
        2. 8.3.10.2 Pattern Checker
        3. 8.3.10.3 Eye Opening Monitor
      11. 8.3.11 Interrupt Signals
    4. 8.4 Device Functional Modes
      1. 8.4.1 Supported Data Rates
      2. 8.4.2 SMBus Master Mode
      3. 8.4.3 Device SMBus Address
    5. 8.5 Programming
      1. 8.5.1 Bit Fields in the Register Set
      2. 8.5.2 Writing to and Reading from the Global/Shared/Channel Registers
    6. 8.6 Register Maps
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Front-Port Jitter Cleaning Applications
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
      2. 9.2.2 Active Cable Applications
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
      3. 9.2.3 Backplane and Mid-Plane Applications
      4. 9.2.4 Design Requirements
      5. 9.2.5 Detailed Design Procedure
      6. 9.2.6 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.5 Detailed Design Procedure

The design procedure for backplane/mid-plane applications is as follows:

  1. Determine the total number of channels on the board which require a DS250DF210 for signal conditioning. This dictates the total number of DS250DF210 devices required for the board. TI recommends that channels with similar total insertion loss on the board be grouped together in the same DS250DF210 device. This simplifies the device settings, as similar loss channels generally utilize similar settings.
  2. Determine the maximum current draw required for all DS250DF210 retimers. This may impact the selection of the regulator for the 2.5 V supply rail. To calculate the maximum current draw, multiply the maximum transient power supply current by the total number of DS250DF210 devices.
  3. Determine the maximum operational power consumption for the purpose of thermal analysis. There are two ways to approach this calculation:
    1. Maximum mission-mode operational power consumption is when all channels are locked and retransmitting the data which is received. PRBS pattern checkers/generators are not used in this mode because normal traffic cannot be checked with a PRBS checker. For this calculation, multiply the worst-case power consumption in mission mode by the total number of DS250DF210 devices.
    2. Maximum debug-mode operational power consumption is when all channels are locked and retransmitting the data which is received. At the same time, some channels’ PRBS checkers or generators may be enabled. For this calculation, multiply the worst-case power consumption in debug mode by the total number of DS250DF210 devices.
  4. Determine the SMBus address scheme needed to uniquely address each DS250DF210 device on the board, depending on the total number of devices identified in step 2. Each DS250DF210 can be strapped with one of 16 unique SMBus addresses. If there are more DS250DF210 devices on the board than the number of unique SMBus addresses which can be assigned, then use an I2C expander like the TCA/PCA family of I2C/SMBus switches and multiplexers to split up the SMBus into multiple busses.
  5. Determine if the device is configured from EEPROM (SMBus Master Mode) or from the system I2C bus (SMBus Slave Mode).
    1. If SMBus Master Mode is used, provisions must be made for an EEPROM on the board with 8-bit SMBus address 0xA0.
    2. If SMBus Slave Mode is used for all device configurations, an EEPROM is not needed.
  6. Make provisions in the schematic and layout for standard decoupling capacitors between the device VDD supply and GND. Refer to the pin function description in Pin Configuration and Functions for more details.
  7. Make provisions in the schematic and layout for a 25MHz (±100 ppm) single-ended CMOS clock. Each DS250DF210 retimer buffers the clock on the CAL_CLK_IN pin and presents the buffered clock on the CAL_CLK_OUT pin. This allows multiple (up to 20) retimers’ calibration clocks to be daisy chained to avoid the need for multiple oscillators on the board. If the oscillator used on the board has a 2.5 V CMOS output, then no AC-coupling capacitor or resistor ladder is required at the input to CAL_CLK_IN. No AC coupling or resistor ladder is needed between one retimer’s CAL_CLK_OUT output and the next retimer’s CAL_CLK_IN input. The final retimer’s CAL_CLK_OUT output can be left floating.
  8. Connect the INT_N open-drain output to an FPGA or CPU if interrupt monitoring is desired. Note that multiple retimers’ INT_N outputs can be connected together because this is an open-drain output. The common INT_N net must be pulled high.
  9. If the application requires initial CDR lock acquisition at the ambient temperature extremes defined in Recommended Operating Conditions, take care to ensure the operating junction temperature is met as well as the CDR stay-in-lock ambient temperature range defined in Timing Requirements, Retimer Jitter Specifications. For example, if initial CDR lock acquisition occurs at an ambient temperature of 85ºC, then maintaining CDR lock would require the ambient temperature surrounding the DS250DF210 to be kept above (85ºC – TEMPLOCK–).