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AFE7444: LMFSHd

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Replies: 5

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Part Number: AFE7444

Hi,

I'm new to high speed data converters. The AFE7444 has LMFS specified in the data sheet. However, there are 5 numbers instead of 4. As such, I guess that the last one is for the "Hd" part. What does Hd mean?

Kind regards,
Imran

  • Hey Imran,

    High density is 1 ( HD =1) if a single sample is broken up into pieces and transmitted over multiple lanes. The only mode that uses HD=1 is Mode 1 which is only available for the AFE7422.

    Thanks

    Yusuf
  • In reply to Yusuf%20Agoro:

    Dear Yusuf,

    thanks for the quick reply.

    So do I understand correctly that the table found in the datasheet here:

    http://www.ti.com/lit/ug/slau783/slau783.pdf

    on the first page, shows a column for TX LMFS and in the first data row shows 84111, that this corresponds to the configuration:

    L = 8, M=4, F=1, S=1 and Hd=1?

    And a second question: "transmitting a sample broken up into pieces over multiple lanes"

    Using this as a reference:

    https://e2e.ti.com/blogs_/b/analogwire/archive/2014/09/24/jesd204b-determining-your-link-configuration

    Since within the JESD204B interface there seems to be a strict hierarchy such that

    1 link contains L lanes
    1 lane contains M frames
    1 frame contains F octets
    1 octet contains S bits

    how does it make sense to break up a sample over multiple lanes? Naively, I would think that this sounds like some sort of compression technique or coherent transmission. Is there any white paper or such, where I could read up on this? Or if it's simple enough, could you please clarify? Is there any description on the HD mode?

    Kind regards,
    Imran

  • HI Imran,

    I've forwarded your question to a device expert. You should get a response soon.

    Jalen
  • In reply to Yusuf%20Agoro:

    I saw the message "TI thinks it's resolved". I have posted a followup question however, to clarify the issue. Could you please answer to the followup?

    Kind regards,
    Imran
  • In reply to Imran Khan46:

    Imran,

    Reference the following JESD format table for TX LMFS = 84111. Notice how the sample for channel I is 16 bits total ( i0[15:0] ). Yet in a single frame half of the 16 bit sample is in lane 1 (  i0[15:8] ) while the other half is packaged in lane 2 ( i0[7:0] ). Because of this Hd aka high density is set to 1. 

    Hopefully this answers your question. 

    Yusuf 

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