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DS32EV400: Extending DisplayPort cable length

Dominic F
Prodigy 20 points
Part Number: DS32EV400

Hello! I have been searching for an IC for the purpose of extending a DisplayPort cable length to up to 20 meters for driving one Full HD monitor. I plan on putting the device in the middle of the cable to re-condition the signal. According to my research so far, the simplest solution appears to be the DS32EV400, Quad Equalizer (http://www.ti.com/lit/ds/symlink/ds32ev400.pdf).

This equalizer clears out the intersymbol-interference of the 4 DisplayPort main-links, and then boost the signals with a limiting amplifier. According to page 13, I should pull all BST_N to high if I am to place the device at 10 meters.

1) Is this IC is suitable for my application (cable extension)?
2) Other than ISI and voltage drop that this chip presumably can deal with, there might also random jitter and phase distortion. In my knowledge, equalizer cannot deal with them. Should I be concerned?
3) It appears that AUX and HPD are left untouched. I believe HPD is just a discrete signal, so that's okay. But can the AUX signal travel for 20 meters without equalizing and boosting?
4) Are there any other IC that I should be looking into? The design will not be able to support I2C.

Thank you for your help!

  • 0
    TI__Guru* 76130 points
    Moving to high speed interface
  • 0
    TI__Mastermind 23815 points
    Hi Dominic,

    Certainly, you need a redriver, do you know what DisplayPort version are you using?
    This device supports up to 3.2Gbps, DP1.1 supports up to 2.7Gbps and DP1.2 supports up to 5.4Gbps
    We have DP130 limited redriver for DP1.2, DP159(as DP retimer) to compensate jitter.

    We don't really provide supported length because not all cables have the same losses and other effects as jitter, bandwidth limited channel, and x-talk can affect the signal integrity.

    The DP130 monitors link training and configures itself accordingly to set voltage swing and pre-emphasis.
    The EQ depends on PE settings, when there is no PE, the maximum EQ at 2.7GHz(5.4Gbps) is 15dB.

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 20 points

    Hi Moises,

    Thank you for your response! DP version is 1.2 for single channel FullHD video. I am just trying out this device to see if this will work.
    For PCB layout, I understand that a 4-layer board (HIGH_SPEED_SIGNAL/GND/POWER/LOW_SPEED_SIGNALS) is recommended. For the 4 high-speed differential main-links, impudence will need to be matched by setting the trace length to be the same, ensure the two differential traces are symmetric, no via, and use small SMD (0402?) coupling caps. Are there more things I can do to ensure the signal integrity will be maintained? Questions I can think of - It is always better off to minimize trace length? How do I know what is the right trace width? I understand that DP impedance is 100Ohms. For a standalone extension board, do I need to match the impedance with a resistor at the input and/or output?

    Thanks you!

  • 0 in reply to Dominic F
    TI__Mastermind 43795 points

    Hi,

    I would use 0402 or 0201 size capacitors.

    Use 100 Ohm differential traces.  The trace width will be determined by the board dielectric dimension and the distance between the traces.  In gneeral I prefer to use lightly coupled traces when space allows.  Tighter coupling is required at connectors and in the breakout region around the device.

    No resistors are required at the input or output of the DS32EV400.

    Regards,

    Lee