Differential output DACs, can I use only one output.

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Hi,

I have a AD1853 DAC differential output current DAC. Can I check if it is okay to use only one of the current output instead of both the outputs as a single ended output DAC?:confused:

Yes, you can, one caveat, make sure you load both outputs equally, also, you may have to return the I/V resistor to Vref, not ground to make sure the DAC works correctly.

Ciao T
 
oon,
I believe what Thorsten meant was to make sure to use the same impednace on both the + and - outputs of your DAC chip. If you're taking signal from the + line and it's loaded with 3k ohms for example also put 3k ohms across the - output even if you don't take any signal from there. The DAC chip will work best with equal resistance on both output phases.
 
Hi,

The chip is a single supply 5v, so the voltage at the output should be loaded to 2.5V, vref. Since the ideal load is 0ohm or input of an IV converter, I think it would be to just short it to vref..

Okay, so you worked it out. When you asked "what is loading" I decided I had started something I was unwilling to finish.

Some comments, if you are going to use Op-Amp I/V anyway, use the OPA1632. It has many great advantages in such an application, like balanced inputs and outputs, so it makes a balanced I/V converter, very low noise, folded cascode singe gain stage architecture and very good output buffers. So you end up with a system having two equal but opposite polarity outputs so you can easily take a single ended output.

Otherwise, remember that an Op-Amp I/V circuits input only looks like a short at DC and very low frequencies...

If you where (for arguments sake) using tubes or maybe discrete J-Fets and wanted to avoid the balanced to se conversion, then loading both DAC outputs with identical I/V conversion RC (or whatever) combinations and using the signal from only one would be the choice, however.

I hope the above helps make your choice.

Ciao T
 
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