SNLS685 December   2020 DS160PR412


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and 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 DC Electrical Characteristics
    6. 6.6 High Speed Electrical Characteristics
    7. 6.7 SMBUS/I2C Timing Charateristics
    8. 6.8 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Linear Equalization
      2. 7.3.2 Flat Gain
      3. 7.3.3 Receiver Detect State Machine
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active PCIe Mode
      2. 7.4.2 Active Buffer Mode
      3. 7.4.3 Standby Mode
    5. 7.5 Programming
      1. 7.5.1 Control and Configuration Interface
        1. Pin Mode
          1. Four-Level Control Inputs
        2. SMBUS/I2C Register Control Interface
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 PCIe x8 Lane Switching
        1. Design Requirements
        2. Detailed Design Procedure
        3. Pin-to-pin Passive versus Redriver Option
        4. Application Curves
      2. 8.2.2 DisplayPort Application
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
  11. 11Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information



Receiver Detect State Machine

The DS160PR412 deploys an RX detect state machine that governs the RX detection cycle as defined in the PCI express specifications. At device power up or through manually triggered event using PD or SEL pin or writing to the relevant I2C/SMBus register, the redriver determines whether or not a valid PCI express termination is present at the far end of the link. The RX_DET pin of DS160PR412 provides additional flexibility for system designers to appropriately set the device in desired mode according to Table 7-2. For the PCIe application the RX_DET pin can be left floating for default settings.

Note power up ramp or PD/SEL event triggers RX detect for all four channels. In applications where DS160PR412 channels are used for multiple PCIe links, the RX detect function can be performed for individual channels through writing in appropriate I2C/SMBus registers.

Table 7-2 Receiver Detect State Machine Settings
PDRX_DETRX Common-mode ImpedanceCOMMENTS
LL0Always 50 ΩPCI Express RX detection state machine is disabled. Recommended for non PCIe interface use case where the DS160PR412 is used as buffer with equalization.
LL3 (Float)Pre Detect: Hi-Z
Post Detect: 50 Ω.
TX polls every ≈150 µs until valid termination is detected. RX CM impedance held at Hi-Z until detection Reset by asserting PD high for 200 µs then low.
HXHi-ZReset Channels 0-3 signal path and set their RX impedance to Hi-Z
LXPre Detect: Hi-Z
Post Detect: 50 Ω.
Reset Channels 4-7 signal path and set their RX impedance to Hi-Z.