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CC2564C: CC2564C routing problems

Zhonghui Xu
Expert 5445 points

Part Number: CC2564C

Hi team,

I have questions from customer:

we are using the bluetooth module CC2564C but we have some routing problems:
1) Referring to SWRA420B.pdf document “CC2564x PCB Guidelines”, fig.6 /page6 shows the RF signal path from device pad B8 to decoupling C31 : well, I’m sorry buit we cannot follow your evaluation board routing because of the presence of local fiducial.
So, can we have problems if the routing between C31 and FL1 is a short linear connection? Please can you verify our routing solution below?

first image I attached before is from gerber files.

the next one is from PCB Guidelines.

2)Figure14 shows the path starting from C25 to pad B15 and then to B26 and B27 on the other device side: it seems on top layer without vias, but this is not possible because of clearance constrain between centerpad of CC2564x. This because comparing the reference gerber file and datasheet the centerpad offset in gerber file is on the right side but in the datasheet is on the left side on top view. So, can we route with vias and without problem? What about this difference?

figure 14 refers to the previous document and the attached pictures are from datasheet and gerber.

Thanks,

Best regards,

  • 0
    TI__Mastermind 48541 points

    Hi Zhonghui,

    1) As long as the customer uses the following guidelines of the RF trace, it is okay not to replicate our reference design:

    • RF traces must have 50-ohm impedance
    • RF trace bends must be made with gradual curves, and 90 degree bends must be avoided.
    • RF traces must not have sharp corners.
    • RF traces must have via stitching on the ground plane beside the RF trace on both sides
    • RF traces must be as short as possible

    2) I'm looking at Figure 4-1 in the datasheet. If you were to rotate this diagram vertically, the centerpad offset would still be on the right side. The customer should be able to modify the clearance constraint to replicate our reference design. I recommend that vias not be used. 

    BR,

    Seong

  • 0 in reply to Seong Kim
    TI__Expert 5445 points

    Hi Kim,

    Thank a lot for your help.

    Sorry  for my later reply, and now I can send you the picture of the best routing we can do. 


    Please let me know if it should be ok or we can have some RF problems.

    Best regards,

  • 0 in reply to Zhonghui Xu
    TI__Mastermind 48541 points

    Zhonghui,

    Please request a design review here and provide all design files needed to do so.

    Thanks,

    Seong