LMX2531LQ2570E

Sebeom Rho

Other Parts Discussed in Thread: LMX2531

6330.Schematic_RegisterMap_SerialData.zip

Hello,

I am trying to generate1250MHz clock using LMX2531. Attached are schematic, register map and serial data timing diagram captured by oscilloscope. I think there were no problem but I can't get the1250MHz clock from FOUT pin.Please could you review if there were some mistake in the attached file?

Thanks, Sebeom

over 9 years ago

0 Dean Banerjee over 9 years ago

TI__Mastermind 27661 points

Sebeom,

I looked at it and found a few things, but not sure if I found anything that would be enough to cause this not to lock. See attachment.

Regards,

Dean8055.LMX2531 Locking Issue.docx

0 Sebeom Rho over 9 years ago in reply to Dean Banerjee

Prodigy 150 points

Dean,

I updated your comment. See attachment.

Thanks, Sebeom

0513.8055.LMX2531 Locking Issue_140925_Sebeom Updated.docx

0 Dean Banerjee over 9 years ago in reply to Sebeom Rho

TI__Mastermind 27661 points

Yes, this should be 0. It is a bit that impacts the VCO calibration. I thought I entered it from the register map, but maybe I made a typo.

Dean

0 Sebeom Rho over 9 years ago in reply to Dean Banerjee

Prodigy 150 points

Dean,

What happen if this NC pin connected to GND? Our artwork engineer connected to this pin to GND.

Sebeom

0 Sebeom Rho over 9 years ago in reply to Dean Banerjee

Prodigy 150 points

Dean,

I have not found the solution untile now.

What happen if this NC pin is connected to GND? Our artwork engineer conntected this to GND.

Sebeom

0 Dean Banerjee over 9 years ago in reply to Sebeom Rho

TI__Mastermind 27661 points

Sebeom,

This is an issue. The inductor for the VCO tank is formed by bond wires that connect to this pin and the ones below it. If it is grounded it can cause the VCO to oscilllate at a higher frequency, or likely not at all.

Regards,

Dean

0 Sebeom Rho over 9 years ago in reply to Dean Banerjee

Prodigy 150 points

Dean,

There was something wrong because this NC pin connected to GND. We reworked this pin and the device is working well now. Thansk for your support.

Thanks,Sebeom

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LMX2531LQ2570E