DS90UB954-Q1: No sync mode to operate without external REFCLK

Tomohiro Nagasawa58

Part Number: DS90UB954-Q1
Other Parts Discussed in Thread: DS90UB953-Q1,

Dear Support team

In the data sheet, it seems that there is no description of no sync mode to operate without external REFCLK, is it recommended?

Regards

Tomohiro Nagasawa

over 7 years ago

0 Palaniappan Manickam over 7 years ago

TI__Genius 10475 points

Nagasawa-san,
953/954 supports synchronous mode so the 953 does not need an external reference clock in this mode.
This is covered in detail in the 953 datasheet clocking modes section and clocking system diagram (Figure 9).

0 Tomohiro Nagasawa58 over 7 years ago in reply to Palaniappan Manickam

Expert 1570 points

Hello Palaniappan-san

Thank you for reply.

I understand DS90UB953-Q1 without external clock.

But can DS90UB954-Q1 support non-sync mode without external clock?

Regards

Tomohiro Nagasawa

0 Palaniappan Manickam over 7 years ago in reply to Tomohiro Nagasawa58

TI__Genius 10475 points

Nagasawa-san,
Ok thanks for clarifying your question.
The 954 can come up and establish lock without the external clock by using its internal clock.
However keep in mind the this internal clock can vary in frequency so this will not have sufficient accuracy for the CSI-2 interface and also can cause variation in the forward channel or backchannel timing. So external refclk should be applied to the 954 regardless of the clocking mode on the 953 side.

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DS90UB954-Q1: No sync mode to operate without external REFCLK