DS90UB913A-Q1: CML output frequency isn't synchronized with PCLK

Yaita-san,

I am taking a look into this issue and will provide a scopeshot of the PCLK vs output and see if I can try to replicate your issue. Do you have access to one of our compatible deserializers such as the 914? 

If so, I would like to know if you have the same issue when connected to a deserializer.

Regards,

Jonny

Hi Jonny-san,

>Do you have access to one of our compatible deserializers such as the 914? 
>If so, I would like to know if you have the same issue when connected to a deserializer.
Yes, I connected DS90UB913A-CXEVM with DS90UB914A-CXEVM (deserializer), external PCLK and FPD LNK III output were synchronized normally in this case.
I would like to know if it is possible to synchronize FPD LNK III output with external PCLK when using only DS90UB913A-CXEVM itself (not connected to DS90UB914A-CXEVM).

The background of the question is my customer considers to evaluate output waveform quality of his system in PCLK mode without connecting Deserializer.

Best Regards,
Yaita

Yaita-san,

I attempted to replicate the issue you described in the previous E2E post, but was unable to.

I first connected the whole system link (913 + 914 + cable) and saw that the PCLK and outputs were synchronized. When I disconnected the 914, the output was still synchronized with the PCLK. 

Is the switch S2 on your EVM set to the right setting - Internal PCLK or External OSC?

Is this an issue you only see with one device or multiple? What value of the external oscillator are you using on the PCLK Input pins?

Regards,
Jonny

Hi Jonny-san,

I appreciate for your attention to the inquiry.

Yes, we also confirmed the result.
However DS90UB914A-CXEVM should be connected at the beginning in this case.
I would like to know if it is possible to synchronize FPD LNK III output with external PCLK when using only DS90UB913A-CXEVM itself (not connected to DS90UB914A-CXEVM).

Is it possible?

Best Regards,
Yaita

Yaita-san,

I performed tests that had the 914 connected initially, and then disconnected.

I also ran tests with just the 913, and in both cases, the FPD Link III output was synchronized with both external PCLK and internal oscillator.

Would you be able to provide a register dump for your device so that I can compare the register settings?

Regards,

Jonny

Hi Jonny-san,

>I also ran tests with just the 913, and in both cases, the FPD Link III output was synchronized with both external PCLK and internal oscillator.
Did you refer you could synchronize FPD Link III output with external PCLK using 913 EVM only from start to end? (not using 914 EVM)
It is strange because there is difference between your result and us.

I put register dump as the following. (using 913 EVM only: FPD Link III output isn't synchronized with external PCLK)

I put additional information (Note 1 to 3) for your reference.

Note 1) External PCLK & Serial Out of DS90UB913A EVM without connecting DS90UB914A EVM from start (power-up) to end


Note 2) External PCLK & Serial Out of DS90UB913A EVM after connecting DS90UB914A EVM


Note 3) EVM Jumper/Switch settings


Best Regards,
Yaita

Hi Jonny-san,

>How many devices have you seen this issue on?
My customer saw the issue with his EVM and  we saw with our EVM, so 2/2. 

>Have you tried operating the device in different modes with different PCLK frequencies applied?
We tried "External Oscillator mode" in addition to "PCLK from Imager mode" with 25MHz and 50MHz however the result is all the same (not synchronized).

Please let me confirm about "synchronized" meaning.
We saw the following waveform to judge if serial data outputs based on external PCLK or internal oscillator.
-----------------------------------------------------------
Note 1) External PCLK & Serial Out of DS90UB913A EVM without connecting DS90UB914A EVM from start (power-up) to end <- PCLK and Serial data are not synchronized



Note 2) External PCLK & Serial Out of DS90UB913A EVM after connecting DS90UB914A EVM <- PCLK and Serial data are synchronized


-----------------------------------------------------------
Could you check your waveform in this point?

Best Regards,
Yaita