Good news! A new datasheet for this device appeared on the SI Labs
website today that details all of the registers!

On May 25, 9:41*am, Kendal Goodson wrote:
Hello all,

Has anybody yet played with or seen the Si535x clock generator chips
that showed up in the new Mouser catalog? *It's i2c programmable (like
the si570) and I was thinking that it could be used in a similar
fashion as the si570 usb controlled vfo's that seem to be so common on
the internet. *The 535x series can generate 3 (or 8) different
simulaneous clocks at any one time and I see some advantages to that,
i.e. downconverter oscillator + vfo + detector oscillator all in one
10 pin package. BUT, and there's always a but, the datasheet doesn't
show how to set up the divider registers, instead referring you to a
PC program that will generate programming for you.

Has anybody skinned this cat yet and figured out the register
programming?

73,
Kenn
KA5KXW