When I read the AD650 Data Sheet, I find
so I have a question whether I should tie all signal ground to polygon analog ground? and does it matter?
The AD650 specifies that the analog signals must be referred to the analog ground (pin11). If in your board there is a separate plane for Analog ground which is connected to the pin11, then the analog signal can be referred to this plane. But for the one shot capacitor, I recommend to be place near the AD650 and referred to pin11 directly.
Thank you for your help!
Now I have some question of AD652, Could you help me?
In positive input voltage and dual power supply configuration, the output is not stable. The duty of the output wave always change. And the picture of wave is below:
What can be sure is that output increases when input increases.
Besides the clock output is below:
I am not sure whether it matter?
I'm looking forward to your reply!
May I know how did you connect the configuration of the AD652? The Output frequency should change whenever there is a change of the input voltage.
Thank you for your reply!
I'm sure my input is stable, because I use a constant voltage source as input source.
My AD652 main circuit and clock circuit are below. I design the main circuit following the dual power supply bipolar input mode. The capacitor in right is passby capacitor.
And the clock signal is below:
I am not sure whether the clock circuit has problem?
This is PCB. The U2 is a 6N137 (opticalcoupler). I seperate DGND and AGND by designing two isolated polygon plane. The polygon picture is below:
The left polygon plane is AGND polygon, and the right is DGND polygon.
I use two power supply as digital power and analog power respectively. Becuase output wave's duty always changes, the scope can't lock the wave, the wave on scope is mussy. I aquire the wave picture When I enter the stop button on scope.
These are my detail question, could help me? Whether my PCB has any mistake? I am looking forward to your reply!
Thank you in advance!
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