CDCE949: maximum Skew between Two CDCE949

Ahmed Fendri

Part Number: CDCE949
Other Parts Discussed in Thread: LMK04832

Hello,

Two CDCE949 are connected in parallel and are fed by the same input clock (20 MHz).

What is the maximum Skew between a signal from the first devide and a signal from the second?

Please note that the first device will deliver 9 signals with 40MHz frequency and the second will deliver 3 signals with 40MHz and 2 signals with 20MHz frequency.

Best regards

Ahmed Fendri

over 4 years ago

0 Hao Z over 4 years ago

TI__Mastermind 18070 points

Hello Ahmed,

I'm not sure I understand the question. Are you trying to achieve synchronization between two devices?

Regards,
Hao

0 Ahmed Fendri over 4 years ago in reply to Hao Z

Prodigy 20 points

Hello Hao,

Yes, a synchronization between two devices is needed and thus the output signals also. This is why I need to know the maximum Skew between a signal from the first devide and a signal from the second.

Regards

Ahmed

0 Hao Z over 4 years ago in reply to Ahmed Fendri

TI__Mastermind 18070 points

Hi Ahmed,

This is not how synchronization is typically done. You'll need to either make the phase relationship between two devices deterministic or enable the outputs of two devices in the same time otherwise the output dividers won't be aligned. Synchronization can be done using either zero delay mode or SYNC pin. See attached draft appnote for more information. CDCE949 does not support synchronization across multiple devices. You should probably consider the LMK devices instead. Recommended part is LMK04832.

Multi LMK0482x SYNC, for customer, pre-release draft 2019-01-23.pdf

Regards,

Hao

Clock & timing

Clock & timing forum

CDCE949: maximum Skew between Two CDCE949