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Old 2nd March 2010, 02:51 PM   #11
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It's admirable (in a way) that you took on this project. I'm in the midst of building one of these myself and after looking at the datasheets for a long time it looks like you took alot of shortcuts... I think it's a dis-service to others to make statements like "Please note that however TI claims the IC to be operated safely under 50 Volts"... The engineers behind these devices know a "little something" about what they are doing. If you are serious about building amps like this perhaps you should take a look at the reference design (complete with schematic, Gerber files for PCB and BOM).
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Old 2nd March 2010, 03:25 PM   #12
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Quote:
Originally Posted by 81bas View Post
Instead of writing of 1000 words, I post the link to the datasheet here: http://focus.ti.com/lit/ds/symlink/tas5630.pdf (reference design on pages 25, 26)
Oh, the reference design....... keyword reference.

Quote:
A local ground area underneath the device is important to keep solid to minimize ground bounce.

Last edited by theAnonymous1; 2nd March 2010 at 03:29 PM.
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Old 3rd March 2010, 04:17 PM   #13
m-tech is offline m-tech  Serbia
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Is that heatsink big enough for 7812 powered by 32V ?
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Old 3rd March 2010, 04:26 PM   #14
81bas is offline 81bas  Germany
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Quote:
Originally Posted by m-tech View Post
Is that heatsink big enough for 7812 powered by 32V ?
TAS5630 chip draws only about 100mA from GVDD (+12V), so at 32V there will be 20V lost on 7812, which is 20V*0.1A = 2 Watts.
More dangerous is to use these regulators because of their overvoltage protection. They usually switch off at 35-40V, leaving output mosfets without control with high voltage still applied to them...
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Old 8th April 2010, 08:43 AM   #15
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Quote:
Originally Posted by 81bas View Post
TAS5630 chip draws only about 100mA from GVDD (+12V), so at 32V there will be 20V lost on 7812, which is 20V*0.1A = 2 Watts.
More dangerous is to use these regulators because of their overvoltage protection. They usually switch off at 35-40V, leaving output mosfets without control with high voltage still applied to them...

This might not be a problem because the output mosfets are immediatly into high impendance state as soon as the GVDD is under operating voltage.

secondly, If I use snubber at output ( 10nF + 3R3 ), the resistance burns out immediatly in 2-3 seconds. I have even tried a 5w resistor but it also gets hot enough to touch. Can anybody clarify the reason please. Also when using only 10 nF, the circuit works perfect. The inductors used are exactly 7uH.
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Old 8th April 2010, 09:57 AM   #16
81bas is offline 81bas  Germany
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Quote:
Originally Posted by jash2008 View Post
If I use snubber at output ( 10nF + 3R3 ), the resistance burns out immediatly in 2-3 seconds.
This is because of parasitic oscillations, which occur because of incorrect layout... And this is the reason, why your amp cannot work at voltages higher than 35-40V, as you written before.
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Old 8th April 2010, 10:18 AM   #17
81bas is offline 81bas  Germany
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Simply place at least 1uF SMD ceramic caps as shown in the picture, and parasitic oscillation will go away (I am sure for 99% ) Also, carefully check the PCB after changes made, to do not produce any short circuits under caps, between neighbour traces and soon...
Attached Images
File Type: gif cap.GIF (180.5 KB, 1081 views)

Last edited by 81bas; 8th April 2010 at 10:23 AM.
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Old 8th April 2010, 08:34 PM   #18
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Quote:
Originally Posted by 81bas View Post
Simply place at least 1uF SMD ceramic caps as shown in the picture, and parasitic oscillation will go away (I am sure for 99% ) Also, carefully check the PCB after changes made, to do not produce any short circuits under caps, between neighbour traces and soon...
Thanks
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Old 11th April 2010, 05:17 PM   #19
rajudp is offline rajudp  India
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hi jash
have your problem ( burning resister ) rectified by adding 1uf capacitor
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Old 11th April 2010, 07:04 PM   #20
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Arrow My design for TAS5615

Hi here is my PCB design with full ground shield[single layer] for TAS5615. But it is pin compatible for TAS5630 also.... I going to test the PCB in a couple of days.....
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