lm3886 single sided pcb - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 24th October 2008, 01:36 PM   #1
ryan750 is offline ryan750  Philippines
diyAudio Member
 
Join Date: Oct 2007
Default lm3886 single sided pcb

hi guys,

please check my one sided LM3886 pcb layout, thanks

Click the image to open in full size.

here is the schematic

Click the image to open in full size.

note: input potentiometer is omitted on the pcb
  Reply With Quote
Old 24th October 2008, 01:46 PM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
you pulled the schematic from the National datasheet.
But, you forgot to read the rest of the datasheet.
As a result you have omitted many components that are recommended by National.
Start again.
__________________
regards Andrew T.
  Reply With Quote
Old 24th October 2008, 07:35 PM   #3
ryan750 is offline ryan750  Philippines
diyAudio Member
 
Join Date: Oct 2007
thanks andrew

i've updated the schematics, hope this okay

Click the image to open in full size.
  Reply With Quote
Old 24th October 2008, 08:51 PM   #4
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Hi,
You might want to consider splitting the ground into signal ground and common ground. Separate the two with a low value resistor 10R - 22R.
Like this:
Attached Images
File Type: png 115.png (19.0 KB, 1600 views)
  Reply With Quote
Old 25th October 2008, 04:20 AM   #5
ryan750 is offline ryan750  Philippines
diyAudio Member
 
Join Date: Oct 2007
@MJL21193
what would be the benefit of that??

btw: i've made a pcb layout, any comments??


Click the image to open in full size.
  Reply With Quote
Old 25th October 2008, 06:32 AM   #6
diyAudio Member
 
Join Date: May 2008
Big, unconnected copper areas are an absolute no, no. Either connect them to ground or use that space to make some fixing holes.

Leave some room between the copper and the PCB's border. Remember that a PCB will be produced on a bigger piece of board, which will later be cut to size. Copper right at the cutting edge is likely to be damaged during that process.

Try to keep straight paths at right angles, and make turns at 2x45°. Looks also count. And put yourself into the place of an electron. You are travelling through the copper at nearly the speed of light, and then suddenly there is a 90° turn in front of you. Boy, will you hit your head.

click me

The resistor between signal and power ground can help you with hum issues. You may not need it, but your PCB should be prepared to refit it.
  Reply With Quote
Old 25th October 2008, 07:05 AM   #7
diyAudio Member
 
Join Date: Jan 2008
Just a friendly reminder, and I quote from wikipedia, because my physics textbooks are too far away from my desk:

Quote:
http://en.wikipedia.org/wiki/Electric_current#The_drift_speed_of_electric_charg es

Electric currents in solids typically flow very slowly. For example, in a copper wire of cross-section 0.5 mm˛, carrying a current of 5 A, the drift velocity of the electrons is of the order of a millimetre per second
It is only when considering group velocity that electric current moves rapidly (think of toppling dominoes).

For High Frequency work, those layout guidelines matter. For audio, not so much - just look at the sample PCB's in the datasheets for some of the National chipamps. You're quoting from a guide to switchmode power supplies, which are indeed high frequency devices.

All that said, I hate it when components on a PCB don't sit straight, and I'd never make one up from random angles myself, but that's for purely aesthetic reasons. If it looks good, it'll work well, everything else being correct.
  Reply With Quote
Old 25th October 2008, 08:50 AM   #8
ryan750 is offline ryan750  Philippines
diyAudio Member
 
Join Date: Oct 2007
thanks for the reply guys,

here is the updated pcb layout, anything wrong??

Click the image to open in full size.
  Reply With Quote
Old 25th October 2008, 09:06 AM   #9
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Pin 7 to power ground. The currents from this pin are not clean.

0u1F decoupling? On the back adjacent to the chips power pins?
Use the space just to the left of pin 2 to insert these small decoupling caps. Tie the junction of these caps to the power ground using a short link.

Zobel from output to power ground?

Remove the trace from power ground to signal ground. Insert a pair of holes for a link/resistor to tie these together.

There are sufficient pins to support this chip to the PCB. Break off the three unused pins and use the space freed up to ease your routing.

Q.)
Where should pin 8 go? Is it clean enough to tie into the signal ground or should it go to the power ground?
__________________
regards Andrew T.
  Reply With Quote
Old 25th October 2008, 10:18 AM   #10
ryan750 is offline ryan750  Philippines
diyAudio Member
 
Join Date: Oct 2007
hi,

i this ok??

Click the image to open in full size.

0.1uf wil be soldered directly to the chip
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Single sided non inverting LM3886 PCB tla-Audio Chip Amps 35 1st April 2009 07:16 AM
My tiny single sided LM3886 PCB layout. :) Russ White Chip Amps 74 14th September 2008 06:53 PM
pa100 pcb single sided layout lm3886 dgaxeman Chip Amps 6 24th May 2006 01:45 AM


New To Site? Need Help?

All times are GMT. The time now is 11:13 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2