ADS41B29EVM: ADS41B29 eval board + FMC-ADC-adapter has LVDS lines reversed (P for N)

david royle

Part Number: ADS41B29EVM
Other Parts Discussed in Thread: ADS41B29

We have ADS41B29 eval board, using FMC-ADC adapter rev D to connect to Xilinx board. LVDS P on ADC board connects to LVDS N on adapter.

over 5 years ago

0 RJ Hopper over 5 years ago

TI__Mastermind 18095 points

Very likely. P and N lines are often swapped for layout routing reasons. FPGA FW can easily flip signals as needed. --RJH

0 david royle over 5 years ago in reply to RJ Hopper

Intellectual 440 points

Yes, but this is not a transceiver so it is a little more than just flipping polarities. The DDR clock is also inverted so a delay will be needed on odd bits to get them realigned with the corresponding even bits.

0 Kang Hsia over 5 years ago in reply to david royle

TI__Guru 71079 points

Hi David,

I am assuming the ADC is interfacing with the FPGA. If so, the FPGA pin assignment should allow you to invert both the LVDS Data bus and also the LVDS clock to allow basically transparent capture. The layout has to be done with inversion to avoid crossing. I have checked the ADC datasheet and did not locate the LVDS bus inversion capability. This means that you either have to invert the P/M on your FPGA capture card PCB traces or through the FPGA pin assignment

If you can advise the FPGA that you are using, I can ask around here at TI to see if FPGA pin assignment can allow for the inversion for your particular FPGA.

-Kang

0 Kang Hsia over 5 years ago in reply to Kang Hsia

TI__Guru 71079 points

Hi David,
I have not heard back from you on this issue. I will close this post but you may respond back if further support is needed

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ADS41B29EVM: ADS41B29 eval board + FMC-ADC-adapter has LVDS lines reversed (P for N)