NEW DAC project released->Please comment!!

kimschips · 25th September 2005, 03:30 PM

Hello every body.

This is the schematic for the new dac project that I and Pred is working on now

Please comment what you like and don´t like!!

But no discussion off OS versus NON Oversampling!!

PCM1798 are dual mono
PCM1794 can also be used
All 22uF caps are Oscons SP
100nF and 10nF are ceramic X7R
TL431 from Onsemi have very low noise
Ferrite beads are from farnell (which to use?)

Are the connections for LRCK,SCLK,SDATA clear enought??

Input CS8416:

http://5577.freewebpage.org/PCM1798.jpg

AD1896->2*PCM179X (in paralel)->Ext clock:

http://5577.freewebpage.org/PCM1798A.jpg

Best regards
Kim

kimschips · 25th September 2005, 03:40 PM

To get the links working:
Rightclick->mark and paste into your browser

Best regards
Kim

peranders · 25th September 2005, 04:02 PM

The 431 misses the series resistor in all locations, it's a shunt regulator you know.

Guido Tent · 25th September 2005, 04:14 PM

Quote:

Originally posted by peranders
The 431 misses the series resistor in all locations, it's a shunt regulator you know.

it will also shunt without the resistor :-)

kimschips · 25th September 2005, 04:57 PM

Yes I knew that will come

I have wrote CCS for each shuntleg. A CCS will set the current for each TL431 for about 50mA + Chip current

I can put in resistors-> because each CCS can be a serie reg instead-> up to people

Thank you both

Kim

Guido Tent · 25th September 2005, 05:15 PM

Quote:

Originally posted by kimschips
Yes I knew that will come

I have wrote CCS for each shuntleg. A CCS will set the current for each TL431 for about 50mA + Chip current

I can put in resistors-> because each CCS can be a serie reg instead-> up to people

Thank you both

Kim

Hi

Good !. A small resistor + bead in series with the CCS will maintain high impedance beyond the 1st pole of the CCS.

best

kimschips · 25th September 2005, 06:05 PM

Guido could you please explain that a bit

How do you mean with a CCS 1th pole? where CCS impedance stop falling or is it to define a safe work area?

What is the difference between a 47uH inductor and a Ferrite Bead?

Forgot to tell
I am using Left justified format ok?

Best regards
Kim

peranders · 25th September 2005, 06:38 PM

Quote:

Originally posted by Guido Tent
it will also shunt without the resistor :-)

Sure but not for long. :No:

Guido Tent · 26th September 2005, 05:49 PM

Quote:

Originally posted by kimschips
Guido could you please explain that a bit

How do you mean with a CCS 1th pole? where CCS impedance stop falling or is it to define a safe work area?

What is the difference between a 47uH inductor and a Ferrite Bead?

Forgot to tell
I am using Left justified format ok?

Best regards
Kim

Hi Kim,

Yes, 1st pole is where output impedance decreases. Inductors are often wirewound, whereas a bead uses les windings (sometimes 1 only) and ferrite material to raise impedance.

best

kimschips · 26th September 2005, 06:03 PM

Thanks Guido

The wirewound itself-> will it limits it´s high frequency performance?

If you got a big 1mH inductor how big will the performance difference be to an choke bead?

Have you tried Murata 22uF ceramic for decoupling (X5R, SMD1206)??

Have you guys any other comments to the schematic??

Kim

25th September 2005, 03:30 PM	#1
kimschips diyAudio Member Join Date: Dec 2004 Location: Denmark	NEW DAC project released->Please comment!! Hello every body. This is the schematic for the new dac project that I and Pred is working on now Please comment what you like and don´t like!! But no discussion off OS versus NON Oversampling!! PCM1798 are dual mono PCM1794 can also be used All 22uF caps are Oscons SP 100nF and 10nF are ceramic X7R TL431 from Onsemi have very low noise Ferrite beads are from farnell (which to use?) Are the connections for LRCK,SCLK,SDATA clear enought?? Input CS8416: http://5577.freewebpage.org/PCM1798.jpg AD1896->2*PCM179X (in paralel)->Ext clock: http://5577.freewebpage.org/PCM1798A.jpg Best regards Kim

25th September 2005, 04:02 PM	#3
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	The 431 misses the series resistor in all locations, it's a shunt regulator you know. __________________ /Per-Anders (my first name) or P-A as my friends call me

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25th September 2005, 03:40 PM	#2
kimschips diyAudio Member Join Date: Dec 2004 Location: Denmark	To get the links working: Rightclick->mark and paste into your browser Best regards Kim

25th September 2005, 04:57 PM	#5
kimschips diyAudio Member Join Date: Dec 2004 Location: Denmark	Yes I knew that will come I have wrote CCS for each shuntleg. A CCS will set the current for each TL431 for about 50mA + Chip current I can put in resistors-> because each CCS can be a serie reg instead-> up to people Thank you both Kim

25th September 2005, 06:05 PM	#7
kimschips diyAudio Member Join Date: Dec 2004 Location: Denmark	Guido could you please explain that a bit How do you mean with a CCS 1th pole? where CCS impedance stop falling or is it to define a safe work area? What is the difference between a 47uH inductor and a Ferrite Bead? Forgot to tell I am using Left justified format ok? Best regards Kim

26th September 2005, 06:03 PM	#10
kimschips diyAudio Member Join Date: Dec 2004 Location: Denmark	Thanks Guido The wirewound itself-> will it limits it´s high frequency performance? If you got a big 1mH inductor how big will the performance difference be to an choke bead? Have you tried Murata 22uF ceramic for decoupling (X5R, SMD1206)?? Have you guys any other comments to the schematic?? Kim

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