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TLK2541 at 50 MHz

Aleksander Strel'nikoff
Prodigy 40 points
Other Parts Discussed in Thread: TLK1501

Hi!

TLK2541 has "frequency range of TX_CLK is 100 MHz to 130 MHz". But my FPGA is too slow and does not give correct output data at 106,25 MHz. I use 8B/10B encoder, FibreChannel End Of Frame Correction Mode and half rate mode.

Can I enable a full rate mode and use 53,125 MHz TX_CLK to get 1,0625 Gbps on subject output?

What is the reason for this restriction of TX_CLK ?

Thanks.

P.S.: Sorry for my english :)

  • 0
    TI__Mastermind 20820 points

    Hi Alek,

    Can I enable a full rate mode and use 53,125 MHz TX_CLK to get 1,0625 Gbps on subject output?

    No, the REF_CLK frequency mist be in the range of 100mHz-130Mhz regardless of mode of operation.

    What is the reason for this restriction of TX_CLK ?

    This is the way that the PLL was designed for this part.

    Could you consider using the TLK1501? This will give you your required data rate and runs of a slower REF_CLK. 

    Regards,

    Mike

  • 0 in reply to Michael Peffers
    Prodigy 40 points

    Hi, Mike! Thanks for your answer.

    Yesterday  TLK2541 was work at 53,125 MHz and even 26,5625  MHz. I understand, that such use is not correctly, but my device is already assembled and I have not choice.

    The  TLK1501 is not suitable for me, because I have more number of K characters to transmit. Also I need a FibreChannel End Of Frame Correction Mode, but TLK1501 has not such mode.

    Generally,  I completely satisfied with TLK2541 and will use more fast FPGA in the future.

    Regards,

     Aleks.

  • 0 in reply to Aleksander Strel'nikoff
    Prodigy 40 points

    Hi again!

    I have a new problem with TLK2541.

    Manual says about FibreChannel End Of Frame Correction Mode:

    "In this mode, a K28.5 D21.4 D21.x D21.x EOF is presented to the transmit parallel bus for all EOF ordered sets, and the TLK2541 substitutes a D21.5 in place of the D21.4 on those occasions where a K28.5 D21.5 D21.× D21.× is the proper EOF to be generated."

    I found that device place D21.4 instead of D21.5, I do not need that substitution. For example, if I need tj transmit SOF: K28.5 D21.5 D22.2 D22.2, device is transmit K28.5 D21.4 D22.2 D22.2. 

    Substitution of D21.4 to D21.4 is in manual, but revers substitution...

    it was designed or I doing something wrong?