TUSB9261: Jitter spec violation

Takashi Onawa

Part Number: TUSB9261

Hi team,

My customer noticed that a oscillator which is connected to TUSB9261 can not meet its jitter requirements described in 6.8 Oscillator Specification, Datasheet.
What kind of risks will be estimated such the condition?

According to slla315e.pdf, it seems that USB3.0 feature require tight jitter spec but they don't plan to use USB3.0, USB2.0 only in their use case.

Here is their Oscillator's spec

Phase jitter　⇒　1.0 ps max. (0.4 ps typ)
Period jitter (TJ)　⇒　80 ps typ.

Regards,

Takashi Onawa

over 1 year ago

0 Malik Barton57 over 1 year ago

TI__Guru 64326 points

Hi Onawa-san,

If jitter spec is not meet then normal operation may not be achieved or intermittently interrupted even if USB 2.0 is only used.

0 Takashi Onawa over 1 year ago in reply to Malik Barton57

TI__Genius 13200 points

hi Malik-san,

OK, I understood that it should meet the requirements for interoperability.

Could you tell me the meaning of "JTF" described in the datasheet? do you think this spec meets the requirements?

Phase jitter　⇒　1.0 ps max. (0.4 ps typ)
Period jitter (TJ)　⇒　80 ps typ.

Regards,

Takashi Onawa

0 Malik Barton57 over 1 year ago in reply to Takashi Onawa

TI__Guru 64326 points

Hi Onawa-san,

JFT stands for jitter transfer function. The relevant spec here is "Tp-p Reference clock jitter". The max Tj peak-to-peak should be 50 ps.

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TUSB9261: Jitter spec violation