AnsweredAssumed Answered

What input is the AD5933 expecting?

Question asked by Cannonball2134 on Oct 3, 2012
Latest reply on Oct 10, 2012 by Cannonball2134
Branched from an earlier discussion

Hello,

 

Thank you everyone for your suggestions so far. However there are just a couple of things i still need some help with.

 

At the moment i am trying to determine the gain for an instrumentation amp (IA) that is measuring an unknown impedance, but i need to know what the AD5933 is expecting. I have the AD5933 set to output 1.98Vpp, with a DC bias of 1.48V, does this mean that the ADC input is expecting a value that will vary +- 1.98V around the 1.48DC bias? i.e a maximum of 2.47V, min of 0.49V?

 

I also need to determine an output resistor to convert the IA voltage into current (as shown as Rseries in the grounded impedance App notes (Figure 2)), what current is the AD5933 expecting?

 

Is there a calculation or method for determining the RFB feedback resistor? I will eventually want to measure impedances from roughly 100 up to 2000 ohms.


I believe all these questions are linked, but i'm missing some vital info that is stopping me from answering them. I have read through the data sheet and the App notes, but i seem to be missing something.


Any help would be really great.

Many Thanks,

 

James

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