Part Number: CDCE6214-Q1
Can you provide equations for calculating IP_XO_CLOAD and IP_BIAS_SEL_XO?
I am using a 25MHz crystal with 8pF load capacitance and 100Ω ESR. The traces are very short and copper planes are cut out below the crystal. Routing capacitance should be minimal.
I do not see equations in the data sheet or register map documents.
Also the loop filter settings provided in Table 3 of the data sheet are not labeled the same as the register fields or the selections in TICS Pro. I think I have decoded most of the settings, but I am still missing R3 and C3.
I am trying to get fVCO=2500MHz from fPFD=50MHz.
Thanks for any advice.
Please find the crystal details in this appnote:https://www.ti.com/lit/an/snaa331/snaa331.pdf?ts=1593562102213&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FCDCE6214-Q1
R3 and C3 are for the third order loop filter to provide additional roll off. They do not change the loop dynamics and are less important. You can use the default settings (R3 = 0 and C3 = 1.2pF) to disable the third order filter. If there're large spurs to be suppressed then the values can be changed accordingly.
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
If you have further questions related to this thread, you may click "Ask a related question" below. The newly created question will be automatically linked to this question.
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. 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.