ADAU1787 DAC single ended output from differential output
Hello,
ADAU1787 has a differential DAC output. My application needs a single-ended output and I am wondering if I can simply ground the negative pin of the differential output? If not, do you have a recommendation for a suitable tiny differential amplifier (preferably BGA)?
Best,
VS
ADAU1787
1787
Integrated/Special Purpose A/D Converters
Audio CODECs
Hello VS,
The best thing to do is to use an Op-Amp to convert the balanced output to a single ended output. This will give you the best level and specifications. However, if you do not want to add another Op-Amp stage then just use one of the outputs and leave the unused pin floating. The outputs are not cross-coupled so you do not want to short an output to ground.
If you use just one pin then the output level will be 6dB less of course.
So your question about a tiny differential amp...? Good question,... It is probably best to ask our linear amplifier group. I think this is the best place to post a question? https://ez.analog.com/amplifiers/differential-amplifiers
Mention that the AVDD is 1.8V so it is for a single ended low voltage and will need to be a rail to rail output.
Dave T
Dear Dave,
Are the differential Dac outputs also ballanced? Could use such an analog tube output stage?
Could it be used by a Cirrus CS4397 dac also?
Tks!!
Hello,
I recently inquired about the single ended verses differential output of the ADAU1787 with the designers of the part.
The ADAU1787 is designed for differential headphone output only. It cannot be guaranteed to meet d/s specifications or other system level requirements (pop for example) in single-ended operation.
The EVAL-ADAU1787Z uses a stereo 3.5mm jack and routes HPOUTL+ and HPOUTR+ through 470uF AC coupling capacitors to allow for a stereo connection to headphones, but this is not recommended for system-level design or final use. It is meant just to provide a convenient way for folks to verify that they are getting sound, in case they do not have headphones to accommodate the differential output of the ADAU1787.
We will be updating the documentation for the EVAL-ADAU1787Z to make this distinction clearer moving forward.
But it is expected that noise performance will not be the same in single-ended mode compared to differential mode. Differential is the only mode supported by the ADAU1787 where the d/s specs can be guaranteed.
With regards to the tube circuit. It certainly looks cool and would probably sound great. It is kind of amusing to think of this tiny part driving this big old tube stage! I would love to hear the results.
Dave T
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