Isolation amplifier-AD294

[pravin310]

Hello .

I have to explain the IC - AD294 as a homework.
I have understood the ISO200 somewhat.

But i just cannot understand the datasheet of AD294 , the circuit is pretty complex and i am a newbie .
What i have understood is that optocouplers have been used here and there is an adjustable gain at input , output or both .
Also there is a buffered output , which i dont really understand .
Can some1 pls clear out the meaning of "buffered output ".?

Also , in the datsheet it's mentioned obsolete , so is AD294 not used anymore ? If yes , why ?

Can someone give me a link or anyplace of reference where i can study the ic - AD294
or can someone possibly explain the working of the circuit .
I am not really getting much from the datasheet.

And lastly , what is the main difference between AD294 and AD293 , except the transformer designs .


Any advice will be much appreciated , thanks !

P.S- I am sorry if i didn't follow the rules of forum but i need the help urgently .

 

[moffy]

It doesn't use opto's it uses a transformer for both power and signal. The signal comes into the + input of A1 and is modulated, then demodulated and fed back to the inverting input of A1. This allows A1 to basically deal with non linearities and gain issues of the modulation/demodulation process. The signal is then demodulated again on the output side of the galvanic isolation and buffered/amplified by A2. A buffer is just something that usually takes a high impedance input and provides a low impedance output.

You are right, the AD294 is quite complex. Obsolete means just that. It must have been quite expensive to manufacture as it's a hybrid.

 

[pravin310]

Thanks.

But , what is the main difference between AD294 and AD293 , except the transformer designs . ????

 

[moffy]

The main difference is in the isolation voltage rating: 2500v vs 8000v. The 294 appears to be qualified for medical use.