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Old 29th September 2013, 10:47 AM   #21
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Are we talking about separate boards for each chip or one-board-fit-all?
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Old 29th September 2013, 12:29 PM   #22
noizas is offline noizas  Lithuania
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Quote:
Originally Posted by Marek View Post
I think we shouldn't leave possibility to use separate analog and digital power supplies because of TI/BB recommendation.Most of DACs works with +/-5V and not every one is TI/BB and some may need separate power to achieve top performance. I think there is also reason why TI/BB use separate pins for analog and digital power.
I see some inconsistency in [-15,-12,-5,GND][GND,5,12,15]. The +15V is useless because TDA1541A use +5 -5 and -15V only.
If this is relly nessesary to minimize number of power pins (I think it is not) I suggest to use bonded -15 and -12V and use separate analog and digital pairs of +/-5V and +/-12V to allow most DACs be implemented in high end fasion.
I'm not sure if we need separate GNDs because as far as I remember it should be connected as close as possible to DAC chips.

So summing up I suggest [-12d, -12(-15)a, -5d, -5a] GND [5a, 5d, 12a, 12d]
or if we want even pin numbr [-12d, -12(-15)a, -5d, -5a] GNDa GNDd [5a, 5d, 12a, 12d]

BTW what kind of connector do you think about?
Hi, I suggest we at first should decide DAC chips we are going to make boards for, later decide exact voltages needed.
Primary list is current output type: AD1865, PCM1704, PCM63, TDA1541.
Those need only -15Va; -5Va; -5Vd; AGND; DGND; +5Va; +5Vd in general.
Earlier I had idea we need separate +12V or +15V for CCS of 2mA injection into TDA1541 outputs, but possibly CCS can run from +5Va input. Connecting CCS to +5V digital does not look correct.

Thanks
Saulius

Last edited by noizas; 29th September 2013 at 12:37 PM. Reason: Added PCM63
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Old 29th September 2013, 01:17 PM   #23
noizas is offline noizas  Lithuania
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Quote:
Originally Posted by Lil Knight View Post
Are we talking about separate boards for each chip or one-board-fit-all?
We are talking about separate board, compatible in digital signals and connectors and size with I2S-PCM board.
It should be designed for set of current type DAC chips to make stereo balanced conversion (actually four PCM channels in dual stereo, one power set per stereo).

In case of big mono DAC chips like PCM63 we are going to have two PCM channels only on core board - this can be stereo or mono balanced, it is up to solution of digital I/O (DL and DR or DL and DLn). In case of mono balanced way I guess power supply should not be dedicated to one DAC chip.

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Old 30th September 2013, 08:21 AM   #24
Marek is offline Marek  Poland
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Now I relized that AD1862 require only one pair of +/-12V because:

"The AD1862 operates with 5 V to 12 V supplies for the digital power supplies and 12 V supplies for the analog supplies.
The digital and analog supplies can be separated for reduced
digital crosstalk. Separate analog and digital common pins are
also provided. The AD1862 typically dissipates less than
300 mW."
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Old 30th September 2013, 12:12 PM   #25
noizas is offline noizas  Lithuania
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Quote:
Originally Posted by Marek View Post
Now I relized that AD1862 require only one pair of +/-12V because:

"The AD1862 operates with 5 V to 12 V supplies for the digital power supplies and 12 V supplies for the analog supplies.
The digital and analog supplies can be separated for reduced
digital crosstalk. Separate analog and digital common pins are
also provided. The AD1862 typically dissipates less than
300 mW."
So we need to add AD1862 to the list:

Current list of DACs: AD1862, AD1865, PCM1704, PCM63, TDA1541.
Voltages: -15Va; -12Va; -5Va; -5Vd; AGND; DGND; +5Va; +5Vd; +12Va.
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Old 30th September 2013, 01:08 PM   #26
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Quote:
Originally Posted by noizas View Post
Can you say which software you used for AD1865 core board schematic?
Possibly I would try to do the same for TDA1541
I'm using Altium for schematics/pcb design.
Ian said: "I'll take care of the PCB design and prototyping."

Quote:
Originally Posted by noizas View Post
I suggest we at first should decide DAC chips we are going to make boards for, later decide exact voltages needed.
Per our discussions with Ian from the I2S-PCM thread, AD1865 and TDA1541A will be the first, probably PCM1704 next.

Quote:
Originally Posted by noizas View Post
Voltages: -15Va; -12Va; -5Va; -5Vd; AGND; DGND; +5Va; +5Vd; +12Va.
Agree we should use separate pins for all voltages. This seems OK for me.
Well, this excludes D20400a which would need +15a but I hardly believe anybody will make a core board for that.
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Old 1st October 2013, 12:34 AM   #27
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Quote:
Originally Posted by vzs View Post
I'm using Altium for schematics/pcb design.
Ian said: "I'll take care of the PCB design and prototyping."


Per our discussions with Ian from the I2S-PCM thread, AD1865 and TDA1541A will be the first, probably PCM1704 next.


Agree we should use separate pins for all voltages. This seems OK for me.
Well, this excludes D20400a which would need +15a but I hardly believe anybody will make a core board for that.
Agree,

One thing is very important: Analog and digital power supply should be separated from each other. As signal source of whole system, AGND and GDND should only be connected at one point on DAC.

By considering mostly we are gonna use good shunt or low noise power supply which has only one voltage output on each, I think we need following power supply options for connectors

+5V, GND (analog)
-5V, GND (analog)
-15V,GND (analog, for TDA1541A only)

+5V, GND (digital)
-5V, GND (digital)

So, at least, 10 pins in total is required for power supply connectors.

Core board works with high performance external IV for sure.

vzs could only decide the size and dimensions after power connectors are determined.

Type and P/N of power connectors and I/V output connectors should be take into consideration.

Ian
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Last edited by iancanada; 1st October 2013 at 12:40 AM.
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Old 1st October 2013, 08:10 AM   #28
Marek is offline Marek  Poland
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Ian,

Do we really need separate GND for every analog and every digital supply on connector? or just common AGND and common DGND (connected only close to DAC chip)?
Please don't leave +/-12V analog for AD1862...
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Old 1st October 2013, 02:39 PM   #29
noizas is offline noizas  Lithuania
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Quote:
Originally Posted by iancanada View Post

By considering mostly we are gonna use good shunt or low noise power supply which has only one voltage output on each, I think we need following power supply options for connectors

+5V, GND (analog)
-5V, GND (analog)
-15V,GND (analog, for TDA1541A only)

+5V, GND (digital)
-5V, GND (digital)
Few power connectors if somehow strange to use with one complex PSU - for example with Oliver's [dvb project] Salas shunt regulator board for TDA1541.
Anyway it is ok, just some of GND pins on core board will be unused.

Quote:
Originally Posted by iancanada View Post
Core board works with high performance external IV for sure.
Zsolt mentioned we should try to make output without current offset.
So I'm sure we need to have CCS of 2mA injection into outputs of TDA1541 on Core Board...
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Old 1st October 2013, 07:28 PM   #30
vzs is offline vzs  Europe
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Quote:
Originally Posted by iancanada View Post
By considering mostly we are gonna use good shunt or low noise power supply which has only one voltage output on each, I think we need following power supply options for connectors

+5V, GND (analog)
-5V, GND (analog)
-15V,GND (analog, for TDA1541A only)

+5V, GND (digital)
-5V, GND (digital)
....
Type and P/N of power connectors and I/V output connectors should be take into consideration.
We should use separate 2pin connectors - so digital supply connectors can be placed away from analog ones - less crosstalk between ground return currents.

As Marek mentioned +/-12 is needed by AD1862. We can use the +/-5V connector (let's better call it +/-Va) for +/-12V in case of AD1862.

Regarding power supply connector: even four of these DACs consume less then 200mA per rail so I think a small sized one is well enough. I like the PH2.0 you're using for its small footprint.

For board output I don't see why we shouldn't use the same 2pin PH2.0
Do you have ideas for better connectors types for the output?

Thanks,
Zsolt

Last edited by vzs; 1st October 2013 at 07:30 PM.
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