Hi,
My customer is using ADS52J90.
My customer thinks a frequency of SYSREF clock must be a multiple frequency of LMFC clock.
If a frequency of SYSREF clock is not a multiple frequency of LMFC clock, What is happen?
Best regards,
Shimiuz
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Hi,
My customer is using ADS52J90.
My customer thinks a frequency of SYSREF clock must be a multiple frequency of LMFC clock.
If a frequency of SYSREF clock is not a multiple frequency of LMFC clock, What is happen?
Best regards,
Shimiuz
Hi Shimizu-san,
We have received you inquiry and will get back to you at the end of the week.
Sincerely,
Olu
Hi Shimizu-san,
Thanks for the email. If SYSREF frequency is not a multiple of LMFC frequency, then SYSREF can be asserted in the middle of a multiframe which can lead to JESD devices resetting and the link not coming up.
Sincerely,
Olu
Hi Shimizu-san,
JESD block refers to the JESD TX block as per Figure 72 on Page 49.
Having a continuous SYSREF signal that is not a multiple of the LMFC frequency means that the JESD link will continually have to reset the phase of the LMFC every time the SYSREF is sampled at the rising edge of the device clock .i.e. continuously restarting a multiframe in the middle of another multiframe.
The JESD204B standard goes into more information about SYSREF, LMFC and multiframe alignment.
Sincerely,
Olu
Hi Olu-san,
Thank you for your reply.
I ask other questions for understanding your answer.
Q1: If having a continuous SYSREF signal that is a multiple of the LMFC frequency, Is JESD Block reset?
Q2: If the reset occur at having a continuous SYSREF signal that is a multiple of the LMFC frequency, Do ADS52J90 and FPGA re-negotiation for link?
Best regards,
Shimizu
Hi Shimizu-san,
If you want to gain a deeper understanding of how SYSREF works within JESD204B, I recommend going over this material.
In addition, most FPGA vendors (Altera, Xilinx) have their own proprietary IP that determines FPGA, JESD TX interaction.
Sincerely,
Olu