How Does the AD208 Iso-Amp Function in High Voltage Applications?

[Pagedown]

How to use the instrumentation amplifier? Is it a voltage follower? Can it be used for isolation?

 

[viscousflow]

Instrumentation Amp is not a voltage follower. It amplifies the difference in voltage.

 

[Pagedown]

So what about isolation amplifier? It can be used to break ground loops?

 

[berkeman]

So what about isolation amplifier? It can be used to break ground loops?

Can you link to a datasheet for an example part?

 

[Pagedown]

I intend to use an op-amp for isolation instead of the isolation transformer. Thus, I haven't come across any in my country but have heard of it.

Is there any useful op-amp which can do isolation?

 

[berkeman]

I intend to use an op-amp for isolation instead of the isolation transformer. Thus, I haven't come across any in my country but have heard of it.

Is there any useful op-amp which can do isolation?

A simple opamp will not give you galvanic isolation. You need to use an isolation amplifier of some sort to get isolation.

There are several types of isolation amplifiers, used for different kinds of applications:

http://en.wikipedia.org/wiki/Isolation_amplifier

http://www.google.com/images?hl=en&source=hp&q=isolation+amplifier&gbv=2&aq=f&aqi=g2&aql=&oq=

I've seen interesting analog optocoupler setups used as isolation amplifiers as well -- I'll have to look for the part. It uses two matched analog opto channels, as I recall. One channel is the reference or feedback, or something to help to linearize the signal opto channel.

What are your bandwidth and signal size requirements?

 

[Mike_In_Plano]

Burr Brown used to make isolation amplifiers, and they were bought up by Ti, so you may find them there.
Then again, there are a number of tricks using transformers and diodes, or opto couplers. For low rate, high pecision, a V/F converter is an old favorite - it's very easy to put through an optocoupler.

- Mike

 

[Bob S]

See block diagram of this AD208 iso-opamp from Analog Devices that uses modulator, demodulator, and transformer coupling to provide over 1 kV of isolation. It is very good for putting on the high (primary) side of 220V and 440V power transformers, for example.

http://www.analog.com/en/amplifiers-and-comparators/isolation-amplifiers/ad208/products/product.html

Bob S