SNLU288 December   2020

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Features
    2. 1.2 Applications
  3. 2Description
    1. 2.1  DS160PR412 and DS160PR421 4-Level I/O Control Inputs
    2. 2.2  DS160PR412 and DS160PR421 Modes of Operation
    3. 2.3  DS160PR412 and DS160PR421 SMBus or I2C Register Control Interface
    4. 2.4  DS160PR412 and DS160PR421 Equalization Control
    5. 2.5  DS160PR412 and DS160PR421 RX Detect State Machine
    6. 2.6  DS160PR412 and DS160PR421 DC Gain Control
    7. 2.7  DS160PR412-421EVM Global Controls
    8. 2.8  DS160PR412-421EVM Downstream Devices Control
    9. 2.9  DS160PR412-421EVM Upstream Devices Control
    10. 2.10 Quick-Start Guide (Pin Mode)
    11. 2.11 Quick-Start Guide (SMBus Slave Mode)
  4. 3Schematics
  5. 4PCB Layouts
  6. 5Bill of Materials

2.5 DS160PR412 and DS160PR421 RX Detect State Machine

Each DS160PR412 and DS160PR421 deploys an RX Detect state machine that governs the RX detection cycle as defined in the PCI Express specification. At power up or after a manually triggered event, the redriver determines whether or not a valid PCI Express termination is present at the far end of the link. The RX_DET/SCL pin of DS160PR412 and DS160PR421 provides additional flexibility to system designers to appropriately set the device in their desired mode, according to Table 2-5.

Table 2-5 4-Level Control Pin Settings
PD PIN LEVELRX_DET/SCL PIN LEVELDESCRIPTION
LL0PCI Express RX detection state machine is disabled. Recommended for non-PCI Express use cases. Inputs are always 50 Ω.
LL1PCI Express RX detection state machine is enabled. Recommended for PCI Express use cases. Pre Detect: Hi-Z, Post Detect: 50 Ω. Outputs poll every approximately 150 μs until three consecutive valid RX termination detections.
LL2PCI Express RX detection state machine is enabled. Recommended for PCI Express use cases. Pre Detect: Hi-Z, Post Detect: 50 Ω. Outputs poll every approximately 150 μs until two consecutive valid RX termination detections.
LL3 (Float)PCI Express RX detection state machine is enabled. Recommended for PCI Express use cases. Pre Detect: Hi-Z, Post Detect: 50 Ω. Outputs poll every approximately 150 μs until a valid RX termination detection.
HXManual reset, inputs are Hi-Z