I've set up correctly one AD9834 with a 25MHz oscillator (those with four pins), but when I change to a 50MHz oscillator and load new data it stops working.
If I first load the frequency register with the 25MHz connected, no matter if I change back and forth between 25 and 50MHz, they both will work (check out the schematic, I merely placed a resistor to create smooth transitions, I'll remove it since I'm not planning to keep both oscillators).
However, if I load the frequency register with the 50MHz connected, no matter if I change back to 25MHz, none generate the appropriate frequency (or no output at all).
It seems as if it couldn't load properly the frequency register with the 50MHz oscillator connected. Why?
Thank you for your hints and help!