I want to use the ADS62P49EVM with the onboard-clocking using the onboard CDCE72010 ("Clock Option 2" as described in section 184.108.40.206 of the User Guide).
For this configuration, I need a chrystal filter of 245.76 MHz, which unfortunately is not populated by default. The desing is obviously meant for a certain filter, as there is onboard matching and a certain footprint, however there is no hint in the documentation for specs of this filter other than the center frequency.
Can anyone give me a hint which filter I can use here?
Alternatively, I could use "Clock Option 3" using the LVPECL connection which does not need this filter. However, section 220.127.116.11 sais this option is "not recommended for SNR critical applications". Why is that so? What is the issue with this configuration? I have seen LVPECL connections between clock cleaners and ADC/DAC devices in many Appnotes, so this seems a quite common way to go.
Thanks for your help,
I just checked the BOM for the EVM and see the crystal filter is from Toyocom:
I found the spec and am attaching it.
Option 3 without a filter will result in lower SNR results due to increased jitter. If there is no bandlimit of the phase noise on the clock input, the phase noise of the other Nyquist zones will fold into the Nyquist zone and increase the noise floor degrading the SNR.
We started a write up of clock jitter and here is a link to the first part:
In this case the CDCE72010 output phase noise would have to be integrated to an offset of ~250MHz while the BPF limits it ~10MHz offset.
I did some research on this "TF2-Q5EC1", and it seems that it is (no longer?) available, at least Toyocom doesnt list it anymore, and the distributors cannot provide it.
Is there any replacement part or other workaround you can recommend, such that I can still use this clocking option on the EVM?
I think this part number might be a ‘TI only’ part number from Toyocom, although we were not trying to hide any details on this item. But this filter is in a common Toyocom footprint and there are standard part numbers for this footprint as well.
Looking at the Epson Toyocom site, I believe
fit the footprint.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.