[sdiy] cs4344 DAC output stage

[Eric Brombaugh]

On 09/13/2012 08:30 AM, julian schmidt wrote:
> Hello all,
>
> I'm designing a cortex M4 based audio/synth board using the cs4344 DAC
> and a cs5343 ADC.

Cool! I've got a couple projects like that in the works too:

http://ebrombaugh.studionebula.com/synth/stm32_4chl/index.html

http://ebrombaugh.studionebula.com/synth/stm32f4_codec/index.html

The hardware design was fairly easy - I'm finding that the firmware is a 
lot more fun.

> As i'm new to designing with DAC/ADCs here's a question.
>
> Is there an opamp needed for the DAC output stage?
> I've seen opamp output stages in quite a few designs using different
> kinds of DACs, but the datasheet for the cs4344 just states some R/C
> filters after the dac output as reference design.

That really depends on the signal input requirements of the equipment 
you're driving it with. The CS4344 data sheet circuit gives a 
recommended hookup for line-level outputs, sufficient to drive ~1Vpp 
signals for typical audio line inputs. It's not enough for the ~5Vpp 
signal levels typically used in modular synthesis applications though. 
In that situation you'll want some gain.

Eric