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Original question:

DS25BR100: CML Repeater Redriver for SGMII and PCIe

DS64BR111: Repeater Configuration and Datasheet Details

Ned Dempsher1
Prodigy 70 points
Part Number: DS64BR111

Hi TI,

I think I found a more suitable repeater for running 1.25Gbps SGMII in the DS64BR111.

I had some quick questions for you though:

- Do you agree that this part should work as well? Should I be able to run it using just the input pins for configuration or do I need an EEPROM or I2C for this lower data rate?

- Is the rise time adjustable? I thought reduction might be better for the longer bit time. Doesn't look like it though.

- Any recommendations for XMT pre-emphasis/RCV CTLE at this lower data rate? We are running through 6 meters of cable.

- I did not understand how the XMT Vcommon mode could vary between 0 to 1.9v (datasheet pg. 7). How is this possible?

- I don't understand what RCV VTX (datasheet pg. 6) is (0.19 to 1.6v). Is this min./max. differential voltage allowed at the receiver?

Thanks Very Much,

Ned

  • 0
    TI__Mastermind 43795 points

    Hi Ned,

    Yes this part will work okay.  You should be able to run it with pin control.  This device will require AC coupling on at least the input pins.  The input termination is tied to a 2.5V internal supply voltage and will not be compatible

    The rise and fall times are not adjustable so it will be important to control the impedance near the DS64BR111 outputs to avoid reflections.

    The OUT_B output can easily support ~ 6 dB of de-emphasis.  However, in pin mode the OUT_A output is limited to 700mV amplitude and de-emphasis is not usable at this lower VOD.  If you need Tx equalization on both outputs, either I2C or EEPROM control would be better.

    The output common mode voltage is not well regulated.  it is typically around 1V, low VOD settings result in higher VCM voltages.  High VOD settings result in lower VCM voltages.

    The Rx input voltage is optimized for 600-1000mv at the connected Tx pins.  The residual signal at the DS64BR111 can be quite small (0.19 volts) and have the eye opening closed due to ISI.

    Regards,

    Lee