LMK03200: Wrong pre-scaled clock is come out

Kazuya Nakai59

Part Number: LMK03200

Hi guys,

One of our customers is evaluating LMK03200 on their own board.

Then they found that a wrong pre-scaled clock is come out when registers of LMK03200 are set before clock is input to OSCin.

Also they found that a correct pre-scaled clock is come out when all resisters (R0~R15) are set after clock input is started.

My questions are follows.

Q1. Must all of LMK03200 registers be set after clock is input to OSCin?

Q2. Is it O.K. that R0~R14 registers are set before clock is input and R15 register only is set after clock is input to OSCin?

Your reply would be appreciated.

Best regards,

Kazuya Nakai.

over 8 years ago

0 Kazuya Nakai59 over 8 years ago

Guru 21645 points

Hi guys,

The customer found the cause of the problem. No corrected square waveform applied to data and clock pin. So registers were not set correctly.

Please let me close this thread.

Best regards,
Kazuya Nakai.

0 Tim Chao Li over 8 years ago in reply to Kazuya Nakai59

TI__Expert 4415 points

Hi Kazuya-san,

Thanks for following up, I will close this thread.

For reference:

1. You do not need to program the registers before clock is input to OSCin, but the device will start up with default register settings, which may or may not be desirable.

2. If a clock input is not present at startup, it is necessary to set R15 to re-run the PLL frequency calibration to allow the PLL to lock after the input is present. Normally frequency calibration runs automatically on power up but if no input clock is set it will not be able to calibrate correctly.

Regards,
-Tim

0 Kazuya Nakai59 over 8 years ago in reply to Tim Chao Li

Guru 21645 points

Hi Tim,

Thank you for the information. I could understand about the device registers deeply.

Best regards,
Kazuya Nakai.

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LMK03200: Wrong pre-scaled clock is come out