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?😕
Thanks.
Oon
Thanks.
Oon
I use only one ouput i+ r+ to a resistor to a srpp and is playing music really nice. The bad thing is that i only get 2 miliamps at output and not 4 ma in differential.
That's an interesting point yeah. It makes me wonder if we couldn't use the other channel in an interesting way to get back to the 4mA again. Just thinking aloud here, don't know if this will work but have you heard of mid-side format for stereo?
Hi,
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
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
What do you mean load the output equally? How would you do that?
Oon
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Oon
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Huh, what do you mean spoke out of turn? Not sure what you mean by that, but an apology is definitely not needed. How did you say I should load them equally?
Oon
Oon
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.
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.
Ok, that makes sense, so if I use it on a normal op amp based I/V stage with a voltage at 2.5V, I would then connect the other ouput differential to a 2.5V source as well... correct...?
Oon
Oon
Oon,
We are discussing resitance loads, not voltage. The + and - outputs should have the same resistance across them to ground.
We are discussing resitance loads, not voltage. The + and - outputs should have the same resistance across them to ground.
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..
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Hi,
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
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
Hey thanks for all the clarification and tips. Really appreciate it. Very likely, I will do nelson pass D1 IV stage.
But the tip on the opamp is really useful.
Oon
But the tip on the opamp is really useful.
Oon
Hi,
If you use this single ended, it is important to remember that it's input impedance is not zero.
Ciao T
If you use this single ended, it is important to remember that it's input impedance is not zero.
Ciao T
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