LMK04906BEVAL: Question about VCXO

Kazuhiko Hirano

Part Number: LMK04906BEVAL
Other Parts Discussed in Thread: LMK04906

Tool/software:

Hello,

Q1:
LMK04906 Evaluation Board User’s Guide (snau126A.pdf) page 35 says “Figure 15 shows the open loop typical phase noise performance of the Epson VG-4231CA 25.0000MFGRC3 VCXO.”. But On page 16, in the Figure 15 plots, it says “CVHD-950-122.88”, it is not Epson VCXO, it is CRYSTEC VCXO name. Which is true, EPSON or CRYSTEC?

Q2:
Table 12 on page 36 and Table 13 on page 40 of LMK048xx Evaluation Board User's Guide on page (snau076B.pdf) are identical. VCXOs are different and their frequencies are also different. Why they are identical?

Best regards,

K.Hirano

1 month ago

0 Michael Srinivasan 1 month ago

TI__Genius 9190 points

Hi Hirano-san,

Q1: The VCXO is the Epson VG-4231CA 25.0000MFGRC3 VCXO.

Q2: I am a bit confused by this question. I looked at the document you mentioned and Tables 12 and 13 specify two different measurements entirely.

Thanks,

Michael

0 Kazuhiko Hirano 1 month ago in reply to Michael Srinivasan

TI__Genius 15138 points

Michael,

Thank you for your responses.
For Q2, The table 12 is on page 35 of LMK04906 Evaluation Board User’s Guide (snau126A.pdf), but the table 13 is on page 40 of LMK048xx Evaluation Board User's Guide on page (snau076B.pdf). Those are not in the same document. But they are identical, why?

Best regards,

K.Hirano

0 Michael Srinivasan 1 month ago in reply to Kazuhiko Hirano

TI__Genius 9190 points

Hirano-san,

That is strange. I looked at the listed datasheets for both devices and the data in the table listed corresponds to the CVHD-950-122.88 or some other 122.88MHz VCXO.

I will look into it in more detail to try to find the data for the Epson VG-4231CA 25.0000MFGRC3.

Thanks,

Michael

0 Kazuhiko Hirano 1 month ago in reply to Michael Srinivasan

TI__Genius 15138 points

Michael,

Any updates on this?

Best regards,

K.Hirano

0 vicente flores prado 1 month ago in reply to Kazuhiko Hirano

TI__Mastermind 29362 points

Hello Hirano-san,
There seems to be some discrepancy, overall, the entire BOM and user's guide lists a 25MHz epson VCXO. I would want to assume that's the case here.

I believe for that to be a typo.

Best regards,

Vicente

0 Kazuhiko Hirano 1 month ago in reply to vicente flores prado

TI__Genius 15138 points

Vicente,

I am asking about Q2.
Why 25MHz VCO phase noise in SNAU126A.pdf is exactly the same as 122.88MHz VCO phase noise in SNAU076B.pdf?

Best regards,

K.Hirano

+1 Michael Srinivasan 1 month ago in reply to Kazuhiko Hirano

TI__Genius 9190 points

Hirano-san,

As Vicente stated, this is a typo for the table describing the 25MHz VCXO. The data in this table corresponds to the 122.88MHz VCXO specified in SNAU076B. I checked the datasheet for the Epson VG-4231CA 25.0000MFGRC3 VCXO, and no RMS jitter data was specified.

Thanks,

Michael

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LMK04906BEVAL: Question about VCXO