Original question:
Hello,
We are able to turn the power to our VCXO off and on, and I have recently noticed that the STATUS_VCXO pin will change to high with no input. I have put a scope on the VCXO output and there is nothing there, but the STATUS_VCXO pin stays high. If I power up the VCXO, then the STATUS_VCXO pin goes high. If I power the VCXO down, the STATUS_VCXO usually goes down, but then it switch back to high after a few minutes. What could the cause of this be?
Thanks,
Todd
Hi Ajeet,
I may have found the problem. Testing has been good so far. I have a single-ended clock output that I convert to differential as such:
I was wondering if when there is no clock the two signals are nearly identical and potentially noise could be picked up and interpreted as an input clock. I adjusted R121 to 120 ohms to adjust one bias a bit and I haven't seen the VCO IRef go high by itself. I see in the datasheet that the Vinpp min is actually 150mV, so maybe that is low enough to pick up some stray noise?
Thanks,
Todd
