Delfino internal clock jitter

Kevin Stallard

Hi,

I guess I'm posting this hoping there is an answer, but also realizing there may not be one. Attached is a scope picture of the PLLRAWCLK divided by 8 running as close to 200 Mhz as possible (don't want to exceed 200 Mhz).

As you can see by the picture there is a lot of jitter. It seems out of spec with the data sheet. It suggests INTOSC2 is going to stay with in 0.1% of 10 Mhz.

I've also attached a picture of using an external 10 Mhz clock. It settles down nicely.

I am using the production version (TMS) of the part. Any ideas on getting the internal oscillator to behave better?

Thanks

Kevin

over 9 years ago

0 Adam Dunhoft over 9 years ago

TI__Expert 7885 points

Hi Kevin,

The 0.1% frequency stability at room temperature is only a typical spec. The accuracy spec for the INTOSC is 10 MHz +- 3%. Also note that there is not a jitter spec for the INTOSC.

Are you using a development board from Texas Instruments or is this your own application board? Is this test the only task running on the device or do you have other application code running as well?

Best Regards,
Adam Dunhoft

0 Kevin Stallard over 9 years ago in reply to Adam Dunhoft

Intellectual 445 points

It is our own board. Using the ZWT BGA.

Does the datasheet specify the accuracy somewhere? The only spec I can find is the frequency stability.

I know this is probably a very crazy question, but it sure would be cool if in another version of the silicon we could see this tightened up...

Thanks Adam
Kevin

0 Adam Dunhoft over 9 years ago in reply to Kevin Stallard

TI__Expert 7885 points

Hi Kevin,

It is not called "accuracy", but rather the frequency spec (MIN 9.7 MHz - MAX 10.3 MHz) is stated in Table 5-18. Internal Oscillator Electrical Characteristics. It is the spec above frequency stability in the same table.

I agree that it would be great if we were able to tighten the frequency spec of the INTOSC. Unfortunately it is not so simple. :) We do appreciate your feedback though and I will be sure to communicate it to our team.

Best Regards,
Adam Dunhoft

0 Kevin Stallard over 9 years ago in reply to Adam Dunhoft

Intellectual 445 points

Thanks Adam

0 Kevin Stallard over 9 years ago in reply to Adam Dunhoft

Intellectual 445 points

And I hear you about the difficulty, but I had to ask :)

C2000™︎ microcontrollers

C2000 microcontrollers forum

Delfino internal clock jitter