Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

My take on a LM3886 layout
My take on a LM3886 layout
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 22nd February 2015, 02:35 PM   #1
sevenup2278 is offline sevenup2278  Netherlands
diyAudio Member
 
Join Date: Sep 2012
Default My take on a LM3886 layout

So I made my version of the LM3886 amplifier on a small 50x35mm board.

I was wondering if a groundplane for the signal part would be better than the current layout. If so, which components can be connected to this groundplane?

I have doubts about the chip pin 7, which now has a separate ground return.

Any other suggestions would be appreciated.
Attached Images
File Type: jpg lm3886.JPG (334.1 KB, 1316 views)
  Reply With Quote
Old 22nd February 2015, 10:03 PM   #2
tomchr is offline tomchr  Canada
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Calgary
Suggested reading: Taming the LM3886 Chip Amplifier

Not bad for a first try. I suggest using a ground plane and turning the VCC, VEE, and OUT routes into pours rather than traces. You might as well minimize the inductance there. I also suggest using a better decoupling network. You can read more on my Taming the LM3886 page linked to above.

~Tom
__________________
Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD. HP-1: 3W/20Ω, -130dB THD, 128dB DNR.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
  Reply With Quote
Old 23rd February 2015, 07:43 AM   #3
sevenup2278 is offline sevenup2278  Netherlands
diyAudio Member
 
Join Date: Sep 2012
So I started with the pours for supply lines and output.

Should the power ground also be a groundplane, or is it ok as is?
Attached Images
File Type: jpg lm3886_2.JPG (332.3 KB, 1238 views)

Last edited by sevenup2278; 23rd February 2015 at 07:54 AM.
  Reply With Quote
Old 23rd February 2015, 08:48 AM   #4
tomchr is offline tomchr  Canada
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Calgary
Not bad. I still suggest a ground plane. At the very least, turn the left half of the board into a plane. You'll get better performance with a full ground plane, though. For actual data, see this thread: http://www.diyaudio.com/forums/chip-...ml#post3846783

~Tom
__________________
Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD. HP-1: 3W/20Ω, -130dB THD, 128dB DNR.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
  Reply With Quote
Old 23rd February 2015, 12:37 PM   #5
sevenup2278 is offline sevenup2278  Netherlands
diyAudio Member
 
Join Date: Sep 2012
Quote:
Originally Posted by tomchr View Post
Not bad. I still suggest a ground plane. At the very least, turn the left half of the board into a plane. You'll get better performance with a full ground plane, though. For actual data, see this thread: http://www.diyaudio.com/forums/chip-...ml#post3846783

~Tom
Tom,

Thanks for your input. I came up with 2 groundplanes, 1 for power / 1 for signal.

Pin 7 of the chip is now connected to the signal ground, is this ok?
Attached Images
File Type: jpg lm3886_3.JPG (362.3 KB, 1163 views)
  Reply With Quote
Old 26th February 2015, 01:49 PM   #6
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
I see 4 components crossing cuts in the ground plane/s.
If I include the chip itself, that makes the count 5 !
__________________
regards Andrew T.
  Reply With Quote
Old 28th February 2015, 08:53 AM   #7
sevenup2278 is offline sevenup2278  Netherlands
diyAudio Member
 
Join Date: Sep 2012
Quote:
Originally Posted by AndrewT View Post
I see 4 components crossing cuts in the ground plane/s.
If I include the chip itself, that makes the count 5 !
Hi AndrewT, thanks for the comments. I can learn a lot from it. Hope this is better.
Attached Images
File Type: jpg lm3886_4.JPG (361.7 KB, 1060 views)
File Type: jpg lm3886_5.JPG (267.0 KB, 1018 views)
  Reply With Quote
Old 28th February 2015, 09:33 AM   #8
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
Now I see one trace joining the two upper planes.

Where do all the lower side traces pass across the cut in the upper plane?
Or do they ALL pass under that tiny linking trace?
__________________
regards Andrew T.
  Reply With Quote
Old 27th March 2015, 07:07 PM   #9
sevenup2278 is offline sevenup2278  Netherlands
diyAudio Member
 
Join Date: Sep 2012
Layout has changed a bit and boards were ordered and received.

Build one and it is ready to test.
Attached Images
File Type: jpg DSC_0473.jpg (484.7 KB, 499 views)
File Type: jpg DSC_0474.jpg (575.7 KB, 532 views)
  Reply With Quote
Old 28th March 2015, 02:46 AM   #10
tomchr is offline tomchr  Canada
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Calgary
Nice! I like it. The Zobel resistor should be a power resistor, though.

You could have minimized the ground impedance a bit by rotating the supply caps and moving the Zobel closer to the IC, but what you have will likely provide the data sheet performance.

The way you joined the ground planes in Post #7 is the way you want the layout. It looks like that's where you landed on the final layout as well.

~Tom
__________________
Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD. HP-1: 3W/20Ω, -130dB THD, 128dB DNR.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right

Last edited by tomchr; 28th March 2015 at 02:48 AM.
  Reply With Quote

Reply


My take on a LM3886 layoutHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
LM3886 Layout ok? Maxxtr0 Chip Amps 111 18th January 2018 07:13 PM
Yet another LM3886 layout... is this any good? hjf Chip Amps 27 11th July 2014 08:53 AM
LM3886 PCB Layout undefinedza Chip Amps 9 5th July 2012 08:52 AM
lm3886 layout jesserparker Chip Amps 1 16th January 2007 11:29 PM
Please check this LM3886 layout for me CJ900RR Chip Amps 7 26th February 2006 09:35 PM


New To Site? Need Help?

All times are GMT. The time now is 04:24 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki