> alan smith wrote:
> > Using a MCP4922 as the source with a 4.096VREF, the output ranges as
> > expected from 0V to 4.09V
> >
> > I followed this with a IS55004 quad opamp, for reasons of
needing0-10V
> > output.  The voltage on the opamp is 24V.  yes I know I need to
adjust
> > the gain to 2.44 to get 0-10V...that can be done after it works at
2X
> >
> > Just the classic 2X gain of a 10K from the (-) to ground and a 10K
> feedback,
> > is not giving me the expected results.  I put in 4.99K compensation
on
> the
> > (+) input.  The output with 0V in, is giving me 1.8V out.  If I
ground
> the
> > (+) input, it runs up to 21V.
> >
> > So what am I missing here?


> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of Dave Tweed
> Sent: 24 April 2010 16:41
> To: piclist@mit.edu
> Subject: Re: [EE] DAC with 2x gain - isnt working as expected
> 
> A negative power supply on the opamps?
> These units do not have rail-to-rail inputs or outputs.
> 
>

Also the ISL55004 has a whopping 200MHz bandwidth and 300V/us slew rate,
yet this circuit has no compensation components.  Chances are it's
hooting away merrily.

Mike

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