LM1875 pcb, need comments.

endia · 2nd March 2005, 04:55 PM

Hello,
i want to build an amp based on lm1875 and planning to etch board by toner transfer method. Schematic is from datasheet. just want to sure if i had a mistake on pcb and learn some possible improvements. Here is pcb;

feedback resistors and 0.1 uF bypassing caps are underneath the board.

thanks.

endia · 3rd March 2005, 04:10 PM

well, a more readible layout is here. any comments?

DC Dave · 4th March 2005, 07:14 PM

You might have trouble with noise the way you are laying the PCB out. You seem to have connected all the grounds to the ground plane, where as these chips perform better if built using a star ground point to ground everything.

Basically you want to establish a ground point (the star ground)on the PCB and connect your 0V from your PSU there along with the speaker ground. Then you want to run all of your power grounds (from the caps) to that point SEPARATELY from the low level input signal grounds which also attach to that point. This should minimize the chance of ground related noise.

If you search this forum you will see many PCB designs for different chips that use this method that you could adapt from.

endia · 5th March 2005, 11:18 AM

DC Dave, thank you very much,
i'll pay more attention for ground point.
thanks.

2nd March 2005, 04:55 PM	#1
endia diyAudio Member Join Date: Sep 2004 Location: istanbul	LM1875 pcb, need comments. Hello, i want to build an amp based on lm1875 and planning to etch board by toner transfer method. Schematic is from datasheet. just want to sure if i had a mistake on pcb and learn some possible improvements. Here is pcb; feedback resistors and 0.1 uF bypassing caps are underneath the board. thanks.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
LM1875 PCB, Which To Use	Paswa	Chip Amps	238	1st November 2011 12:02 PM
LM1875...how low can you go?	Gcollier	Chip Amps	7	6th May 2010 03:43 AM
How hot does an LM1875 get?	Dominique	Chip Amps	15	23rd January 2007 02:13 AM
lm1875	siemensc65	Chip Amps	4	23rd May 2006 03:28 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

3rd March 2005, 04:10 PM	#2
endia diyAudio Member Join Date: Sep 2004 Location: istanbul	well, a more readible layout is here. any comments?

4th March 2005, 07:14 PM	#3
DC Dave diyAudio Member Join Date: Feb 2004 Location: Washington DC	You might have trouble with noise the way you are laying the PCB out. You seem to have connected all the grounds to the ground plane, where as these chips perform better if built using a star ground point to ground everything. Basically you want to establish a ground point (the star ground)on the PCB and connect your 0V from your PSU there along with the speaker ground. Then you want to run all of your power grounds (from the caps) to that point SEPARATELY from the low level input signal grounds which also attach to that point. This should minimize the chance of ground related noise. If you search this forum you will see many PCB designs for different chips that use this method that you could adapt from.

5th March 2005, 11:18 AM	#4
endia diyAudio Member Join Date: Sep 2004 Location: istanbul	DC Dave, thank you very much, i'll pay more attention for ground point. thanks.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)