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Class D Switching Power Amplifiers and Power D/A conversion

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Old 20th April 2013, 06:41 PM   #3441
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In class d, forget all about single sided, it just cannot be done.

Absolute minimum double sided is mandatory with either top or bottom layer beeing a uninterrupted ground plane, well atleast as uninterrupted as possible.

Also don't bother with home etching boards, in the end, placing an order with itead studio will end up cheaper.
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Old 20th April 2013, 06:50 PM   #3442
akraj is offline akraj  Bangladesh
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Hi Tekko:

I can use the whole top layer for gnd pane, should I do that or do I need to divide high power & low power gnd? As described in iraudamp9.

Okay and how to solve power loop puzzle?


Would be great if you can give a ref of good class D pcb without SMD?

Thanks
Raj
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Old 20th April 2013, 08:39 PM   #3443
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I've learned that you cannot get away from smd in order to make a good low emi class d as the leads on through hole components have significant inductance above 20kHz.

No point in dividing the ground plane, best to have it all continous and have everything GND connect to it, however try to keep the current loops as short as possible.
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Old 21st April 2013, 04:29 AM   #3444
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Quote:
Originally Posted by manojtm View Post
Hi Insomnia,

Thank you for using AUD600 amp

I am not discouraging you, your PCB design is not good for class D big GND loop will create more EMI in to the input and it will create cross talk when you using 2nd CH. Using Ground plane for reducing EMI
2. Use c18 close to the MOSFET for reducing EMI & RF
3. I am not suggesting crowbar for class D b'cause any issues causes in your PCB/components will create -Ve supply comes in SP line and it will damage 7414,2110 and MOSFET.

Regards
MANOJ
look attachment

ok have changed and add big Groundplane, is it ok now ?

But in your PCB File cant see Groundplane,
same in Detex Audio IRS 900 - 3000 Series,
only 1 Layer PCB and no Groundplane
Attached Files
File Type: pdf AUD600 Ground Plane DIY.pdf (125.4 KB, 399 views)
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Old 21st April 2013, 04:39 AM   #3445
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heres is the file with 2 Mosfets totem Pole and Ground Plane Bottom Layer

is it ok ?
Attached Files
File Type: pdf AUD 600 2 Mosfets Grouns Plane.pdf (139.1 KB, 366 views)
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Old 21st April 2013, 11:58 AM   #3446
akraj is offline akraj  Bangladesh
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Quote:
Originally Posted by Tekko View Post
I've learned that you cannot get away from smd in order to make a good low emi class d as the leads on through hole components have significant inductance above 20kHz.

No point in dividing the ground plane, best to have it all continous and have everything GND connect to it, however try to keep the current loops as short as possible.
Hi Tekko:

I will use entire top copper layer for ground pane but may not be possible to short the power tracks. I can make it wider, will it help?

Is there any other suggestions?

Thanks
Raj
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Old 21st April 2013, 01:17 PM   #3447
paskal9 is offline paskal9  Malaysia
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Location: the tropics with 97% humidity
Quote:
Originally Posted by Tekko View Post
In class d, forget all about single sided, it just cannot be done.

Absolute minimum double sided is mandatory with either top or bottom layer beeing a uninterrupted ground plane, well atleast as uninterrupted as possible.

Also don't bother with home etching boards, in the end, placing an order with itead studio will end up cheaper.
i have to disagree.

i've been building numerous class d amps, all in single sided that have worked and are still working for months now. even tried switching some of them at 800 khz and they work beautifully.

do bother with home etching. it's much easier, cheaper and faster to produce than ordering them to be made. and you can keep changing the layout and test them for any difference.

i'm only using through holes without any smd, single sided pcb and home etched. and they're happily driving my subwoofers. all 4 of them.
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Old 21st April 2013, 01:26 PM   #3448
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And they produce alot more EMI than a proper double sided board would.

And itead is definately cheaper with 30 dollars shipped for 10 boards, just the copperclad alone where i live cost more than 30 dollars alone, not to mention the chemicals required.
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Old 21st April 2013, 01:28 PM   #3449
paskal9 is offline paskal9  Malaysia
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Quote:
Originally Posted by akraj View Post
Hi Tekko:

I will use entire top copper layer for ground pane but may not be possible to short the power tracks. I can make it wider, will it help?

Is there any other suggestions?

Thanks
Raj
for any kind of useful tips and design guides, google and download these PDF(s). they're application notes and design guides from IR and other manufacturers regarding class D.
Click the image to open in full size.
the most useful ones i've marked '#' (for me at least). they helped me much.

for PCB layout do read International Rectifier's Application Note AN-1135 - PCB Layout with IR Class D Audio Gate Drivers, it has graphics and clear explanation on the most crucial pcb parts, component layout and ground and power planes.
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Old 21st April 2013, 01:42 PM   #3450
paskal9 is offline paskal9  Malaysia
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Quote:
Originally Posted by Tekko View Post
And they produce alot more EMI than a proper double sided board would.

And itead is definately cheaper with 30 dollars shipped for 10 boards, just the copperclad alone where i live cost more than 30 dollars alone, not to mention the chemicals required.
they do, but with proper care, optimized layout and proper sized traces and gap, it could be minimized.
using just one large plane for ground isn't always gonna lower the EMI/RFI/THD.

locality is different for most people in this forum. it costs me USD$10 in parts to UV expose and etch a 15cm x 30cm pcb in 10 minutes. i could have the pcb up and running in less than a day.
and it'll take me ~30 days to order anything from the states and have them arrive at my doorstep.
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