Hi please find attached document for ADG 888 operational problem,
Please suggest where i am going wrong.
As a first test you could swap your Coil-IN2 and REF-IN2 inputs around and see if you see the same votlage shift. It would also be worth checking how the channels you are testing are terminated as well to see if there are any issues there.
Is this is happening due to BREAK-BEFORE- MAKE- TIME DELAY....................which is not provided externally in my circuit.
Can any one suggest on above problem?
Sorry for the delay in replying. We are looking at your request now and will post comments asap.
I think your schmatic is basically ok but I have a few comments/questions. What kind of signal levels are you using on the COIL-IN2 and REF-IN2 channels? If they are above Vdd or below ground then the behavour of the switch would be effected. For the COIL-IN2 channel, is that connected to a large inductance? If so then there would be a large voltage created when the swtich toggles, you would need a snubber accross the load to reduce this voltage (Diode or RC). For completeness I would advise you to ground the IN2 pin and the unused switch pins. Finally to help debug this application I would use simple DC singles on the input to prove out that the switch is working. Then connect your live signals/loads and see if that is where the issue is coming from. I hope this helps.
Thanks for sending reply! To give you more clear picture about Coil-IN2
and REF-IN2, i have attached source circuit detail for your reference.
Coil-IN2 and REF-IN2 are DC signal and there max range is going to be
0-3mV (Max) and they are controlled by Polar-control signal (0-3.2V)
coming from controller.
Basically it looks ok. How are you testing the signals on the "signalw" and "signalb" lines? It would be good to do a single ended measurement on them before and after the switch to see if the ground shifts from one to the other after you throw the switch. Perhaps the TB2 block isn't acting as a proper differential termination and is somehow shorting the signal when it is switched.
As suggested, i looked in different aspect and today i removed TB2
connector and started testing, now my logic is working ie swapping of
signal is happening.
Now it is giving very different problem, please suggest on this-
When my switch is not activated that is D1 connected to S1B and D2
connected to S2B (ie switch NC position) it is showing exact value of
input divider network as output between D1 and D2, ie for input of 2mV i
am getting output as 2mV, for input of 1mV output is 1mV, for input of
0.5mV output is 0.5mV.
But when i activate the switch and D1 get connected to S1A and D2 get
connected S2A (ie Switch NO position) the signal is getting swapped but
amplitude is getting increased by offset, ie for input of 2mV i am
getting output as 2.5mV, for input of 1mV output is 1.25mV, for input of
0.5mV output is 0.625mV.
I am not sure from why this extra voltage is coming into picture, i have
not added any more component in original circuitry (other than removal
of TB2 connector).
Missed to tell you that i have shorted all unused PINS to GROUND and
then only i found this switch working as per logic and found below problem.
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