Well Fred, I didn't say I agreed that their products were better than others, nor that I am awed in any way by their engineering "prowess". Like I said, it seems like nothing more than a prestige / marketing thing. Just look at the way TI markets so many of their products... the numbers are often quite impressive, but their real performance tends to be much more in line with their competitors (TI DSPs vs. AD DSPs, for instance). You have to admit though, they <i>do</i> seem to invest a lot of R&D in some areas, and occasionally release products which out-spec everything else, or beat the competition to the market, and those products are most often too expensive.
I certainly never implied in any way that I thought R2R was better than sigma-delta DACs, or that better specs == better sound. My only point was that TI does like to play the "one-up" game, and hence it's my strong impression that they will release another DAC in the R2R family.
I certainly never implied in any way that I thought R2R was better than sigma-delta DACs, or that better specs == better sound. My only point was that TI does like to play the "one-up" game, and hence it's my strong impression that they will release another DAC in the R2R family.
Yeah, I had a problem in Canada, trying to buy DSPs direct from AD. They were not available from any distributors, and there were only two payment options: CC or PO. POs required an account with AD, and hence a bunch or crazy stuff like trade references and so on... totally out of the question. For CC orders, they would only ship to the US, so eventually I had to have them shipped to an American address and forwarded to me. So the AD buy online thing doesn't even seem to work that well just in N. America!
As for the ADXL-202's, I've received these just as free samples. Is that what you were getting, Sonnya?
As for the ADXL-202's, I've received these just as free samples. Is that what you were getting, Sonnya?
First : Countries from where you can buy online
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Yes it is ADXL-202 i am using for tiltsensing, but i would not use such a unit for motional feedback.
Actually AD have made a paper on motional feedback. where they used a ADXL-250
a bit off-topic.... he he he
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Yes it is ADXL-202 i am using for tiltsensing, but i would not use such a unit for motional feedback.
Actually AD have made a paper on motional feedback. where they used a ADXL-250
a bit off-topic.... he he he
PCM1792 spex and AD1955 samples.
Well, here's a Japanese version of the spec sheet - may not help most of us...
It seems to be all over the Japanese site, but nowhere to be found still ont he US site. (Figures... always behind...)
Japanese PCM1792 datasheet
Anyways, you can get samples of the AD1955 from Analog Devices' website pretty easily...
Start here:
October 2002 DAC Bulletin
and select AD1955's (Datasheet/Sample) at the end of the form. I got samples and datasheets in about a week. Was no problem at all.
However, has anyone here successfully found a way to get samples of the PCM1792, which they said would be available in January?
Well, here's a Japanese version of the spec sheet - may not help most of us...
It seems to be all over the Japanese site, but nowhere to be found still ont he US site. (Figures... always behind...)
Japanese PCM1792 datasheet
Anyways, you can get samples of the AD1955 from Analog Devices' website pretty easily...
Start here:
October 2002 DAC Bulletin
and select AD1955's (Datasheet/Sample) at the end of the form. I got samples and datasheets in about a week. Was no problem at all.
However, has anyone here successfully found a way to get samples of the PCM1792, which they said would be available in January?
TI have mostly launched the PCM1792. It now appears in their parts list under Audio D to A Converters. However when you try to get the datasheet, it says "The information that you have requested is not available for this device." We should see datasheets soon!
One good sign: it's more expensive than the PCM1704.
Update: datasheet at http://www-s.ti.com/sc/psheets/sles069/sles069.pdf
One good sign: it's more expensive than the PCM1704.
Update: datasheet at http://www-s.ti.com/sc/psheets/sles069/sles069.pdf
I've read the datasheet, ant I haven't understood how to use this chip in mono mode (132dB SNR (stereo is 129dB))
they say that to obtain 132dB SNR, you must set the chip in mono mode, and so, both DACs operate in balanced operation
But this chip has already 2 dacs, both balanded.
Another thing I haven't understood is that they talk about 4.5V and 9V output, isn't the PCM1792 supposed to output a current?
they say that to obtain 132dB SNR, you must set the chip in mono mode, and so, both DACs operate in balanced operation
But this chip has already 2 dacs, both balanded.
Another thing I haven't understood is that they talk about 4.5V and 9V output, isn't the PCM1792 supposed to output a current?
"parallel balanced output"
Well you can certainly call it that but it is not the intended use. What they do is convert each balanced output to mono separately, presumably to get the common mode spikes off each line, and more importantly remove any DC offset that probably has to be on the lines!!!. This means that one of these must be inverted for mono mode, either digitally or by swapping + with -
By doing the latter, one could make a stereo DAC in balanced mode without a microcontroller by feeding the same signal into two DAC's. This is what I intend to do.
One could of course go the parallell route instead. I have often pondered what would happen if I hooked up say 16 of these in parallel and staggered their clocks just ever so slightly.
Petter
Well you can certainly call it that but it is not the intended use. What they do is convert each balanced output to mono separately, presumably to get the common mode spikes off each line, and more importantly remove any DC offset that probably has to be on the lines!!!. This means that one of these must be inverted for mono mode, either digitally or by swapping + with -
By doing the latter, one could make a stereo DAC in balanced mode without a microcontroller by feeding the same signal into two DAC's. This is what I intend to do.
One could of course go the parallell route instead. I have often pondered what would happen if I hooked up say 16 of these in parallel and staggered their clocks just ever so slightly.
Petter
What is the "optimal DC level" for the current out?
This probably seems like a strange question. However, I have been burned by the AD1853 which has DC level on the current outputs without that being plainly obvious from the data sheet.
I am now perusing this datasheet and wonder if there is DC level here as well, especially since I don't see a negative supply voltage to the current output stage (it is all referred to ground). Presumably it would have to be, but then again, the buffering op-amps seem to be referenced to ground on the other pins. Hmmm.
Any ideas? Anybody have access to TI experts who might be able to answer us on this?
Edited: I found the chart I was looking for (chart 66 no less): each output is centered around a -6.2mA per pin quiescent current. To me this means that 6.2mA flows into each of the 4 output pins when input signal is bipolar zero. The range on this current is thus -2.3mA to -10.1mA.
This is worth taking into account when designing your circuitry!
Petter
This probably seems like a strange question. However, I have been burned by the AD1853 which has DC level on the current outputs without that being plainly obvious from the data sheet.
I am now perusing this datasheet and wonder if there is DC level here as well, especially since I don't see a negative supply voltage to the current output stage (it is all referred to ground). Presumably it would have to be, but then again, the buffering op-amps seem to be referenced to ground on the other pins. Hmmm.
Any ideas? Anybody have access to TI experts who might be able to answer us on this?
Edited: I found the chart I was looking for (chart 66 no less
): each output is centered around a -6.2mA per pin quiescent current. To me this means that 6.2mA flows into each of the 4 output pins when input signal is bipolar zero. The range on this current is thus -2.3mA to -10.1mA.This is worth taking into account when designing your circuitry!
Petter
Dang!
I went back and evaluated the resistors, gain etc. and found that the DC level of the output current is darn near ground. You can do this trick yourself by multiplying the "measured" output voltage of each of the two extremes + bipolar zero available in figure 66 and apply that to the input op-amps U1 and U2.
That's OK by me, I am just slightly surprised.
Now if you build a nice balanced output stage there, NAR you should be OK!
Petter
I went back and evaluated the resistors, gain etc. and found that the DC level of the output current is darn near ground. You can do this trick yourself by multiplying the "measured" output voltage of each of the two extremes + bipolar zero available in figure 66 and apply that to the input op-amps U1 and U2.
That's OK by me, I am just slightly surprised.
Now if you build a nice balanced output stage there, NAR you should be OK!
Petter
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