I have a question about AD9559 device.
I cannot find the formula to calculate the frequency clamp function in AD9559 datasheet.
Please let me know the formula and some information about the frequency clamp.
Thanks & Best regards,
The pull-in range that's in Registers 0x0405-0x040A is a truncated version of the free-running tuning word (FTW0) in Registers 0x0400. Specifically, it's 20 most significant bits of the FTW0.
The formula for the FTW0 appears on Page 35 of Rev C of the datasheet.
When working with these values, I recommend using the eval software, which can be downloaded here:
All that said, you may have better luck using the reference validation block to limit the frequency excursion of the DPLL.