Guide needed. beginner in learning PCB (DIP-TRACE) - diyAudio
Go Back   Home > Forums > Design & Build > Software Tools

Software Tools SPICE, PCB CAD, speaker design and measurement software, calculators

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 16th July 2010, 10:39 PM   #1
diyAudio Member
 
Join Date: Apr 2009
Send a message via MSN to chchyong89
Default Guide needed. beginner in learning PCB (DIP-TRACE)

Dear everyone, i am new to PCB making, and i am interested in designing a compact SMDs dac for siblings and my girlfriend. I have downloaded a free version diptrace, and my goal is :

-A USB power, i2s out, upsampling, and a WM8741/WM8742.
-Dual layer PCB, no fancy caps, fully smds.


However, i am in the trouble for finding the chips in the diptrace when i started to draw the schematic. Suppose a PCM2707 is using TQFP-32, but i just can't get it find by by entering such keywords under TI. Any others keywords to be search?

A simple guide needed to the way of searching for different chips model in DIP-Trace. utmost appreciate with any helping hand.
__________________
~.~
  Reply With Quote
Old 16th July 2010, 11:03 PM   #2
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Have you tried looking for the package rather than a specific chip?
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 16th July 2010, 11:06 PM   #3
diyAudio Member
 
Join Date: Apr 2009
Send a message via MSN to chchyong89
oh, sorry for the poor england i used:P

i am actually mean how can i search for the package of PCM2707?
There are too many in the TQFP-32 pattern, but none of them are under TI.
__________________
~.~

Last edited by chchyong89; 16th July 2010 at 11:08 PM.
  Reply With Quote
Old 16th July 2010, 11:20 PM   #4
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Your English is OK, I understood what you meant. Sorry I can't help. Maybe just try drawing the layout and leave the schematic.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 17th July 2010, 06:52 AM   #5
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
The package mechanical details and the reccomended footprint to IPC-7351 standard. The IPC-7351 standard for PCB footprints covers nearly all PCB required footprints, I'd say that anyone doing SMD PCB design should follow this standard, if for no other reason that th work has been done for you.
My only comment I'd make initialy can you go to a 4 layer PCB, this will be much easier to lay out and more criticaly better for signal integrity.
I would also recomend using a metric grid (0.05mm) and layout. Have a look for a document "The Cad library of the Future" by Tom Hausherr.
Attached Files
File Type: pdf pcm2707-package.pdf (35.9 KB, 34 views)
File Type: pdf QFP-Footprint.pdf (71.0 KB, 36 views)

Last edited by marce; 17th July 2010 at 06:57 AM.
  Reply With Quote
Old 17th July 2010, 07:11 AM   #6
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Have you looked here,
Attached Images
File Type: jpg DIP.JPG (149.1 KB, 204 views)
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 17th July 2010, 07:15 AM   #7
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Also in the free version of Diptrace the 250 pin limit is restrictive. I find if you use individual pads for as many components as you can rather than actual part outlines then you can go over that limit. I use the part initially for pin spacing etc, then match a pad size to it and drag them in place manually if I go over the limit.
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 17th July 2010, 08:03 AM   #8
diyAudio Member
 
Join Date: Apr 2009
Send a message via MSN to chchyong89
Thanks mooly for the help,
So the FQFP-32/5X5A has the exactly the pin layout of pcm2707 right?

Do you guys straight away start your drawing using PCB-Layout before using schematic?
__________________
~.~
  Reply With Quote
Old 17th July 2010, 08:33 AM   #9
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Having looked at some of my stuff, a double sided layout would be possible (though not easy), but careful attention will be required to ensure you achieve as near as possible a contiguous ground plane on the bottom of the board.
You have picked some fine pitch devices for a first off PCB design. The Wolfson devices at 0.65mm pitch can be very problematic to solder without solder resist between the pins (shorts). And all the integrated packages are prone to coplanarity problems which can lead to bad joints, so a flat finish (not HASL) will be required for the pads.
SMT HANDBOOK - QUALITY ISSUES
Wolson Footprints atached.
I use Cadstar or Allegro, but always the schematic comes first then this is transferred to the PCB directly. Any subsequent changes are done on the scheamtic and ECOed to the PCB. So that the PCB always matches the schematic.
Attached Files
File Type: pdf WM8741-footprint.pdf (70.1 KB, 18 views)
  Reply With Quote
Old 17th July 2010, 11:13 AM   #10
diyAudio Member
 
Join Date: Apr 2009
Send a message via MSN to chchyong89
Thanks marce,

I just finish drawing the layout for the PCM2707 using component editor and attached to FQFP-32/5X5A. "I am kinda worry the footprint matching by the way"

Click the image to open in full size.

The last step, where can i search for the spice model for this 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
PCB Trace widths Mark245 Solid State 19 7th July 2009 09:13 PM
PCB Trace Clearance for High Voltage Bengali Tubes / Valves 3 12th November 2007 03:12 AM
PCB Trace Width Current rating?? Zero Cool Everything Else 9 21st November 2004 07:48 PM
non os for cdp without pcb trace cutting Bernhard Digital Source 16 20th April 2004 03:58 PM


New To Site? Need Help?

All times are GMT. The time now is 03:13 PM.


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