pcm1792 dac - use of the volume control feature

[BrianGT]

I picked up some pcm1792, and I am going to make a dac with them for my cd pro 2, possibly along with the ad1896 (i will swap for the src4192/3 once they are available).

Has anyone tried to use the volume control feature of this dac? The datasheet says 0 to -120db with 0.5db/step, which seems perfectly fine for my use, and it doesn't seem too hard to control, using a pic.

Also, can anyone recommend any good surface mount opto-isolators for the digital control lines for this dac?

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Brian

[sonnya]

Hi, The SRC4192/93 is available .. I got them as samples.

[BrianGT]

Originally posted by sonnya
Hi, The SRC4192/93 is available .. I got them as samples.

really? I requested them, and they said they wouldn't be available until the end of october

I wanted to use the SRC4193, since it has the microcontroller interface. Do you have an extra chip you can spare?

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Brian

[sonnya]

I have 3 SRC4192IDB so yes you can get one of them.

On the SRC4193 page under "samples" there is a sample button at SRC4193IDB...

Sonny

[BrianGT]

Originally posted by sonnya
I have 3 SRC4192IDB so yes you can get one of them.

On the SRC4193 page under "samples" there is a sample button at SRC4193IDB...

Sonny

Actually, all I am looking for is the SRC4193, since it can be controlled by SPI. Thanks for the offer, but i guess I will have to wait for the SRC4193 samples to arrive.

As for the SRC4192, I have the AD1896, which is pin compatible for now to play with, so I don't need the SRC4192.

If anyone else has any extra SRC4193 samples, let me know!

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Brian

[sonnya]

Maybe i will be nice and order it through my new company..... and send you a sample.

I have just registered the domain : www.mirand.dk

I will be up next week.

[BrianGT]

Originally posted by sonnya
Maybe i will be nice and order it through my new company..... and send you a sample.

I have just registered the domain : www.mirand.dk

I will be up next week.

I don't think that the problem is that they won't ship it to me, but instead that they are currently out of stock of this item. I have gotten other samples from them before a few times.

When did you request this item?

Thanks for your generosity.

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Brian

[jewilson]

Brian,

My concern in using a the newer dac for a pot is the linearity of the silicon. Maybe, a R2/R ladder dac, one that has no opamp internal to it that might be the best choice. You might look at some of Analog Devices older parts.

[BrianGT]

Originally posted by jewilson
Brian,

My concern in using a the newer dac for a pot is the linearity of the silicon. Maybe, a R2/R ladder dac, one that has no opamp internal to it that might be the best choice. You might look at some of Analog Devices older parts.

The PCM1792 doesn't have internal opamps, and just outputs current from the dacs, and I plan on making the I/V stage with opa627 opamps.

I don't know of any other dacs with volume controls, besides the ad1955.

What is the best way to put a solid signal into the dac, so that I can do a response graph of the linearity of the volume control? Is there any easy way to input a solid level response into the dac?

--
Brian

[jewilson]

You have to have a dac that has not reference voltage built in.
You would input your signal into the reference input then change the bits.

Now AD use to make these parts but I am not sure anymore. I'll have to check.