Need an opinion..

[si2030]

Hi there,

I want to build a two stage non inverting amplifier with a digital potentiometer controlling both stages. The op amp is analog's AD8599 which can operate up to +/-15volts. The potentiometer is Analog's AD8402 which operates to a maximum votage of 5 volts.

I have created a spice simulation of this to check that the voltage doesnt exceed the potentiometer's specs. In the picture you can see two traces - both of which are significantly below 1 volt - each trace is taken just after each digital pot....

The other thing is that this particular pot runs off a single voltage rail... I note there are a number of dual rail potentiometers available (although much higher resistance)... given this particular application do I need a duel rail pot here...

so...

So based on this can I use this potentiometer in this scenario (given its 5 volt limit)... The spice modelling indicates the potentiometer wont exceed is rated maximum however I was wondering if an informed member might have a look and tell me if this will indeed work?

Kind Regards

Simon

 

[si2030]

Gone to the keeper huh?

 

[misterT]

If I understood the datasheet (AD8402) correctly, the minimum voltage at any of the potentiometer terminals is 0 volts.. according to your simulation, the voltage goes negative.

 

[si2030]

Hi MisterT... I am assuming where it says "Voltage Range" under "Resister Terminals" = 0 - Vdd.. just read it... so I guess this means my spice model is erroneous... OK I shall look for an AC part from analog... Thanks for taking the time to have a a quick look..

Kind Regards

Simon