• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 33 subscribers
  • Views 511 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

DP141RLJEVM: how to use DRV_PK?

DP141RLJEVM: When should enable DRV_PK 6dB AC gain?

Gang Feng1
Prodigy 65 points
Part Number: DP141RLJEVM
Other Parts Discussed in Thread: SN65DP141, TDP142

Hello,

There is a signal chain gain control diagram (Figure 16 in page 14 of the data sheet). It shows that RX dc gain and TX dc gain are configurable. Since the total dc gain should be 0dB, there are actually only two possible configurations with the dc gains: (1) Rx dc gain = -6dB and TX dc gain=6dB; (2) Rx dc gain = 0dB and Tx dc gain = 0dB. Is this understanding correct?

I didn't see the DRV_PK 6dB AC gain in this diagram. Can this Tx side 6dB AC gain stack on the EQ_AC_GAIN? Or, they are effective in different frequency range and won't affect each other?

If the DP141 is put on the far side of the 8m-10m cable,  it is a long input cable case. According to Table 3, the Rx gain should be set to -6dB to get the 7-17 EQ AC gain. I guess in this case, the input swing may not be large. But there seems no setup profile for long input cable small input swing?

Thanks

  • 0
    TI__Guru**** 178126 points

    Hi,

    When TX DC gain = 0, it sets the output linearity range to 600mVpp. When TX DC gain = 1, it sets the output linearity range to 1200mVpp.

    RX DC Gain and EQ0/EQ1 work together to determine the best setting, please refer to Table 3 of the DP141 datasheet for the different scenario. For long input cable, it is assumed that the input swing has be bigger to compensate for the input cable loss.

    Driver peaking adds an extra 6dB of high frequency gain. Boost happens between 6 and 10Gbps.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 65 points

    Hello,

    I am beginning to do the design with SN65DP141 now. Can I have the .brd file of the SN65DP141 evm board for reference?

    In my application, the DP re-driver will be placed in the middle of two 5m long cable. For SN65DP141 and TDP142, which one has higher EQ gain?

    Thanks,

    Gang

  • 0 in reply to Gang Feng1
    TI__Guru**** 178126 points

    Gang

    Please accept my friendship request and I will send you the DP141 board file.

    The DP141 has higher EQ gain than the DP142.

    Thanks

    David