LMK04828: question about SYNC/SYSREF block structure？

Hello,

min hu said:

The SYNC function and SYSREF  are mutually exclusive???

They are mutually exclusive at the same time, however you don't need both at the same time.  The red path is for use with SYNC to synchronize all internal dividers together.  Then you will disable the SYNC to the dividers, and then engage continuous SYSREF.  If you source the SYNC/SYSREF path from the divider and allow the reset of SYSREF divider to occur, yes, you will get a crazy waveform.  I call that SYNCing yourself in the foot.  You don't want to do it.

- Note that continuous SYSREF is recommended primarily for setting up the system, as there will be crosstalk from the SYSREF onto the device clock.  You may or may not find the crosstalk acceptable for your application.

I've attached a older document I have about setting up SYSREF on LMK0482x.  It refers to the CodeLoader software rather than the newer TICS Pro software, but I think you will find it visually helpful.  Also refer to datasheet section 9.3.2.

4857.Key Points to setting up SYSREF on LMK0482x_e2e_2016-06-29.pdf

73,
Timothy