PGA2310 Digital Volume Control

I got a update on new products from Texas instruments by Email today discribing the new Burr Brown digital volume control. The link does not seem to be working, but you may be interested in looking at this device by searching their web site.

Here is a partial copy of the TI news letter.

Texas Instruments Unveils Industry's Highest Performance Audio Volume Control IC for Professional Audio Systems -- PGA2310
TUCSON, Ariz. (Oct. 19, 2001) -- Designed for a wide
variety of professional recording and playback
applications, Texas Instruments (TI) (NYSE: TXN)
introduced the industry's highest performance audio volume
control IC (Integrated Circuit) from the company's Burr-
Brown products division. Featuring 120dB dynamic range,
0.0004 percent distortion (THD+N), -126dB interchannel
crosstalk, and +/-15V analog power supplies, the PGA2310
improves system performance in professional audio
applications such as digital mixing consoles, multi-track
recorders, broadcast studio equipment, high-end A/V
receivers, effects processors, musical instruments, and
high-end car audio systems. See
http://www.ti.com/sc/aap6908u.

I copied this from one of my previous entries in order to start a new thread on this subject.

John Fassotte
Alaskan Audio
http://www.audioamps.com
 
In reference to my previous post for the new TI/Burr Brown PGA3210 digital volume control IC.

I have some interest in testing this device in the future. However I have no time to devote to such a project at the present time since I’ am working hard on a all discrete version of my MOSFET class a power amp.

Since I have very little time to attack new projects right now my contribution would be limited to helping others to develop a test bed for this device when my time allows.

If anyone is interested in my help for testing this device and also has programming experiance with suitable controllers please let me know.
 

paulb

Member
2001-06-01 4:53 pm
Calgary
Hey, John, thanks for starting this thread as I suggested, I thought it deserved better visibility.
I'm interested in this chip, perhaps as an upgrade to my preamp. I'm currently using an SSM2018 voltage-controlled amplifier and am very disappointed (it seems to amplify noise on its supply rails). The micro part doesn't bother me (my background is in firmware), but I don't have a development system at the moment. I'm in the middle of another amp at the moment, so it would be a few months before I could start on it as well. Whatever I build, I'd like it to be accessible to DIYers who don't want to spend money on a development system, so I think I'll start looking for a reasonable platform - something like the Basic Stamp comes to mind.
 
A newbie-question about the PGA2310's "Recommended Connection Diagram"/"Typical PCB Layout Floor Plan" found in the PGA2310's data sheet:

The digital and analog planes are supposed to be connected to each other at a single point. Why do they have to be connected? Why aren't the digital and analog grounds left unconnected with each other, since the chip has a digital ground pin and ground pins for both left and right analog channels? And, in the datasheet connection there are separate digital and analog power supplies.

Janne
 
Janne,

Typically the analog ground and the digital ground should be connected at one point on the printed circuit board using the shortest possible connection between the two. Any traces than may need to route from the analog side to the digital side should be run directly beneath this ground bridge. This is pretty standard practice to minimize the antenna effect that lenghty connections can cause.

I have not looked at this failrly new device carefully and perhaps it is possible to clock data into it using logic and a optical shaft encoder. If the processor/logic could be stopped when no volume changes are made it may make PCB design simpler. A digital readout is also required to know what volume level is programmed in.

Not to many years back I was at a Stereophile show where a digital volume control creaped up to full volume on its own. Luckely this was noticed before it caused damge to equipment and ears.

Some times errors are made on manufactors data sheets that do cause confusion.
 
Link to the data sheet

I have added a link to the data sheet for this device. It looks extremely atractive and will be quite easy to use. I expect that many high quality audio manufacturers will be using it in the future. The high signal levels it can handle should gice plenty of headroom.

Perhaps the link below will save you some time looking for the data sheet.

The link is:

http://www.audioamps.com/diyparts/ics/ics.htm

I have also uploaded the latest diagram of one of my RIAA equalized preamplifiers and a picture of the bare circuit board.

These can be found at:

http://www.audioamps.com/diyparts/pcb/pcb.htm

John Fassotte
 
I have had some CS3310 devices for a while and had no time to play :-( The specs on the Burr Brown PGA3210 "upgrade" sure look impressive; Crystal's CS3310 was no slouch itself.

I was roaming around and found this link. It may be useful to folks looking to prototype quickly. I wanted to build something like this for my prototyping but using an ATMEL AVR device as the micro instead of the PIC.

http://digilander.iol.it/paeng/CS3310_a_stereo_digital_volume_control_.htm

So, has anybody tried the Burr Brown part yet? We're waiting....

Michael
 

paulb

Member
2001-06-01 4:53 pm
Calgary
Michael,
Yes, the Atmel looks like a good choice, a friend is using it and seems quite happy with it.
Maybe I'll get him to write the firmware...
What's the price on the Crystal part? Have you compared the specs? Yes, I could do it myself but thought you might have already done so.
 
Janne, digital and analogue grounds are kept separate to reduce the contamination of the analogue system with noise from the digital domain, which tends to be quite noisy. Connecting at one point in a “star” arrangement minimises contamination while providing a common reference to the two separate, but interconnected, domains.

Hope this helps.

Cheers,

Pete
 
Alaskanaudio and Pete, thanks for explaining about the "ground thing".

I've also got a CS3310, and no time. I bought an Atmel STK 200 proto board and have been doing some experiments with it. I don't have very impressive results yet, just blinking leds and displaying text on an lcd :)

My "master plan" is to make the AVR control the PGA2310. The good thing with the PGA chip is that it accepts up to +-15V for the analog region. No need to build a separate +-5VDC power supply anymore, I can use the same power supply for the PGA's analog region that I will use for the output buffering and headphone driving (probably done with OPA134's).

I wish I had 48 hours in a day so I had time for my projects, too :)

Janne
 
Janne:

I was doing exactly the same thing! You're further than me with the STK200 though. I have a nice flourescent display that I planned to use (same as LCD interface) but I haven't even gotten around to flashing LEDs on the STK200 yet. I have some 8051 experience, so I'm expecting the learning curve won't be steep.

You know, let me check my email. I might even have some code already for the AVR to talk to the CS3310/PGA2310.
Hmmm..... Stay tuned.

Michael
 
Requirements Ideas?

While I may not get to it for a while, I can start thinking about my next project. If I build something I'll make the firmware available, so I'm looking for requirements ideas.

My original thought was to use the micro to sample a potentiometer driven from a DC supply, so as to simulate a standard volume control. However, this may not allow the option of having the micro only "wake up" when the setting is being changed. This could be solvable with a bit of analog circuitry. Other possibilities are:

Up/down volume pushbuttons (maybe cheesy; and probably need to default to a low setting on powerup; need display of some kind to indicate setting?)

Rotary encoder (may be expensive, also need default setting on powerup and display).

Any other thoughts? A single micro could drive multiple PGAs, so this could probably work as a balanced control as well.
 
I recently started using the ATMEL AVR series and its not as difficult as I thought it would be, even learning the assembly language wasn't too hard, designing the software structure is the most difficult part. ATMEL have a fair amount information and software, see http://www.atmel.com. There is even an application note on RC-5 remote control codes.
These chips can also be connected directly to your printer port so there is no need for an expensive programmer.
 
Single board computers

I have used and programmed the ZWORLD line of single board computers for a number of control applications. Perhaps some of their smaller boards which are made for on board control applications can be used. These are are programmed by a special version of C, which they call dynamic C from a host PC. Debugging can be done quite easily.

These boards would be my choice since I'am somewhat familiar with their software, programming and compiling.

This is A link to their site: http://www.zworld.com/

Some may consider these overkill for the job that needs to be done.

paulb,

It would be nice to be able to add a external remote control function along with a front panel control.

I don't care to much for push buttons to control volume and such things. To me a optical shaft encoder is the best choice. Perhaps it can even just drive a simple up/down counter with a power on preset to come up with the binary codes required. This would eliminate the need for any programming or a control processor.

I received several surface mount PGA2310 devices yesterday.

John Fassotte
Alaskan Audio



[Edited by alaskanaudio on 10-24-2001 at 11:33 PM]
 
Another possibility for micros is the Basic Stamp, which is becoming something of a classic. See http://www.parallaxinc.com.
They're based on a PIC micro.

I'd be a little wary of the high-performance boards, they generally have a high clock & bus speed and probably radiate like crazy.

I noticed Parallax also has some RF wireless modules. I hadn't thought of having a remote because I'm usually out of line of sight of the amp, which wouldn't work with an infrared remote.

There should be some DIY-type infrared remote control stuff out there somewhere.
 
Could somebody give me a brief overview of how the serial interface works? I slept through the computer engineering classes and never got into it in my programming classes.

If you could interface with a simple up/down counter, that sounds like the easiest/cheapest way to go.

thanks!

jt
 
"If you could interface with a simple up/down counter, that
sounds like the easiest/cheapest way to go."

I've been working on and off on a similar idea (to drive a
Dallas DS1802), and it's nearly finished. The optical
encoder on the shaft works, the display works, and all the
signal electronics work fine, but I still have to sort out
a bug in the serial interface control. At this point I wish
I had an oscilloscope! Right now I've shelved the project
for a while to concentrate on finishing a couple of power
amps, but I hope to put the final touches to the preamp ing
the not-too-distant future.

My plans and copious notes are at

http://www.soton.ac.uk/~apm3/diyaudio/Preamp.html

I can let you have a (not quite complete) schematic of the
volume control logic if you are interested.

Alex
 
I ran across a schematic for use with some of the low cost Bourns optical shaft encoders a while back. It may be helpfull.

The link is:

http://www.web-ee.com/Schematics/Digital Knobs/Digital Knobs.htm

This web page also provides a link to the Bourns optical shaft encoders.

Alex I intend to look at your drawings a little later today. Thanks for posting your link and info.

John Fassotte
Alaskan Audio