new LM4780 layout, any comments?

BrianGT · 23rd January 2009, 05:45 AM

I haven't built up a LM4780 amp for a while, so I decided to make a new layout.

Goals for layout:
- single LM4780 + PSU on a single board
- able to be used in stereo or parallel
- reasonably compact: 3" x 5.5"
- decently robust power supply
- attempt at decent separation of grounds, allowing for a star ground for the inputs, going back to the main ground, a separate ground return for the output zobel networks and also the output grounds tied back close to the main ground.

What do you guys think?

BrianGT · 23rd January 2009, 05:46 AM

schematic

BrianGT · 23rd January 2009, 05:53 AM

Here is the bottom layer shown on top of the top layer, with the bottom silk screen (OGND is shown in the wrong place currently)

Green = bottom layer
Red = top layer

ratza · 23rd January 2009, 05:20 PM

Excellent. I don't think you can shorten tracks more than they are.

BrianGT · 23rd January 2009, 09:24 PM

My only major concern is leaving enough clearance to attach the chip to the heatsink. I believe that with the large caps pushed back, an angled screwdriver should be able to screw the board into the heatsink.

--
Brian

toolsresearch · 23rd January 2009, 09:29 PM

Quote:

Originally posted by BrianGT
attempt at decent separation of grounds

Great!

Any interest in going back and doing the same for other chips? 3886?

Also, why not make it so that the board could be cut if someone wished to do so?

BrianGT · 23rd January 2009, 10:51 PM

Quote:

Originally posted by toolsresearch

Great!

Any interest in going back and doing the same for other chips? 3886?

Also, why not make it so that the board could be cut if someone wished to do so?

Here is a similar layout that I made for the LM3886, which I haven't finished fully yet.

The idea here is to have a narrow board, so that you can easily pop 2 aside each other for a dual mono amp and avoid having to wire up the power supply board to the amp board. (or to the same effect a 5 channel amp).

-Brian

ratza · 24th January 2009, 10:20 AM

Quote:

Originally posted by BrianGT
My only major concern is leaving enough clearance to attach the chip to the heatsink. I believe that with the large caps pushed back, an angled screwdriver should be able to screw the board into the heatsink.

--
Brian

On my amplifiers I placed the screws behind the heatsink and the nut + washer on the chip or transistors, so this might be an option.

raypalmer · 24th January 2009, 06:58 PM

I love them! I hope it's ready by the time I start my monoblok project.

Ted205 · 24th January 2009, 07:44 PM

would be a shame to have the psu connected as the only option.

23rd January 2009, 05:20 PM	#4
ratza diyAudio Member Join Date: Dec 2007 Location: Sibiu, Romania	Excellent. I don't think you can shorten tracks more than they are. __________________ Any solution is a compromise.

24th January 2009, 06:58 PM	#9
raypalmer diyAudio Member Join Date: Dec 2008 Location: Burlington	I love them! I hope it's ready by the time I start my monoblok project. __________________ Wherever you go there you are.

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23rd January 2009, 09:24 PM	#5
BrianGT diyAudio Moderator Emeritus Join Date: Jan 2002 Location: near Atlanta, GA	My only major concern is leaving enough clearance to attach the chip to the heatsink. I believe that with the large caps pushed back, an angled screwdriver should be able to screw the board into the heatsink. -- Brian

24th January 2009, 07:44 PM	#10
Ted205 diyAudio Member Join Date: Jun 2008	would be a shame to have the psu connected as the only option.

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