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About the eye-patterns corrective strategy of DS80PCI800

Satoshi
Guru 19645 points
Other Parts Discussed in Thread: DS80PCI800

Although DS80PCI800 is evaluated, if it lets a repeater pass, it does not lock well.
I think that jitter will be large if a waveform is seen.
(Eye patterns do not come out well)

Since details are written to below, if there are an adjusting point and proposed measures, please let me know.

---------------------------
- Speed : 3 Gbps
- Cable length of an interface
　The input of a repeater: 2 m
　The output of a repeater: 0.8 m
- The kind of cable
　Input side: Twinax cable
　※It is a cable as shown in the figure below (3 put the Dorain line into the twisted pair of a differential pair).


　Output side: FFC

・measurement waveform.
Near the input pin of a repeater
⇒50Z9 X-pre4 K-MDR-PP-9_VX1RX1A.png （below）


Near the input pin of latter-part IC
⇒58Z9 X-pre4 K-MAIN-PP-8_VX1RX1-EYE.png （below）

 

- A setup of VOD, Equalizer, De-Emphasis, etc. is a default.
* Even if it changes a setup, there is little wave-like change.
---------------------------

Thank you for your consideration.

  • 0
    TI__Mastermind 29655 points

    Hi Satoshi-san,

    The waveforms you are seeing after the repeater show some signs of over equalization. How are you controlling the DS80PCI800? SMBus or Pin Mode? Also, are you using a DS80PCI800EVM right now?

    My guess is that if you are using SMBus mode, you are not seeing any changes in the setup from the default values because the CRC data enable bit has not been set. When debugging, in Reg 0x06, Bit 3 needs to be set as 1, otherwise changes to the EQ, VOD, or DEM will not result in changes at the repeater output.

    Another idea is to set up the device in pin mode and decrease the EQ and DEM. Afterwards, see if the output waveforms are any different from what you are currently seeing.

    Thanks,

    Michael