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ADS42JB49: JESD204b Frame Assembly

John French1
Prodigy 30 points
Part Number: ADS42JB49

I'm a new user of JESD204b interfaces. My question is with respect to Table 6 from the ADS42JB49 datasheet. My application need only use 1 input channel of the converter at 200 MSPS. With this configuration the lane line rate would follow:

Lane line rate = (M x S x N' x 10/8 x FC)/ L

= (1 x 1 x 16 x 10/8 x 200E6)/2

= 2.0 Gbps

This is in compliance with the part specifications maximum SERDES frequency, correct? Or is my calculation incorrect because Table 6 from the data sheet does not indicate M = 1 as a valid parameter for the part?

  • 0
    TI__Intellectual 1180 points

    Hi John,

    I see where there could be some confusion. If you could please give me some time, I will try to find the information that will most benefit you.

    Regards,

    Drew

  • +1
    TI__Intellectual 1180 points

    Hi John,

    The datasheet does seem to imply that M = 2 is a universal value, but this can be changed if you are indeed only using one channel. Since your M and L parameters would both be halved, 2111 for only one channel used would have the same JESD packing as 4211, which is a valid device range as you can see in Table 6. You just need to account for having fewer lanes as well as fewer channels.

    Thanks,

    Drew

  • 0 in reply to Drew Pierpont
    TI__Mastermind 23780 points

    John, 

    As Drew mentioned above, here is a visual of how your configuration will look by ignoring the JESD lanes for channel B in the receiver IP. You can powerdown channel B by using CTRL1 and CTRL2 pins.

  • 0 in reply to Drew Pierpont
    Prodigy 30 points

    Thank you Drew, this is very helpful.