my first try at a LM3886 layout, any comments/suggestions?

BrianGT · 18th January 2005, 03:05 PM

Here is my first try at an LM3886 layout. I have been sitting on this design for about 10 months now, and decided to put the last touchs on it last night. Let me know what you think.

btw: I am still backlogged in mails, and will try to catch up soon.

--
Brian

UrSv · 18th January 2005, 03:25 PM

Looks very good indeed. Can't wait to get myself a few of those.

BrianGT · 18th January 2005, 03:49 PM

Thanks,

With regards to the layout, has anyone tried adding the mute capacitor to the layout? Is this a recommended addition? The datasheet seems to like 100uF for this. I was thinking about possibly adding the cap to the layout, based on a suggestion I received.

Also, would it make sense to add a jumper for allowing the mute functionality to be switched on and off?

--
Brian

r!sc! · 18th January 2005, 04:17 PM

Very nice

Boban

BrianGT · 18th January 2005, 04:26 PM

Here is a version with the Cm cap added:

Datasheet says:
"Mute capacitance set up to create a large time constant for turn-on and turn-off muting."

The value in the datasheet is 100uF, and this will be an optional component, as is the zobel network components.

For using the larger BG capacitors, the cap can be omitted, or stuffed on the bottom of the pcb.

--
Brian

peranders · 18th January 2005, 04:58 PM

You shouldn't snubberize you design? Why don't you add 100 nF/63V polyester/ceramic + 1 ohms so Carlos will get happy? At least 100 nF would be good I think.

The grounding looks good! :up.

BrianGT · 18th January 2005, 05:01 PM

Quote:

Originally posted by peranders
You shouldn't snubberize you design? Why don't you add 100 nF/63V polyester/ceramic + 1 ohms so Carlos will get happy? At least 100 nF would be good I think.

The grounding looks good! :up.

Sounds like an idea for the snubber stuff. I will work up a new power supply board, and see how it looks. I can add a few pads for the localized decoupling caps on the pcb.

--
Brian

BrianGT · 18th January 2005, 06:11 PM

Quote:

Originally posted by peranders
You shouldn't snubberize you design? Why don't you add 100 nF/63V polyester/ceramic + 1 ohms so Carlos will get happy? At least 100 nF would be good I think.

The grounding looks good! :up.

How does this look for the "snubberized" rectifier board?

A few extra pads can be added to the main amp board for the extra decoupling caps.

--
Brian

peranders · 18th January 2005, 06:15 PM

I think you should have this snubber close to the supply pins, not far away.

I think also that the speaker trace is a bit thinn. Remember that you have at least 11 A worst case. I recommend a 150 mils trace.

I would aslo recommend that you make a decent schematic. It must be pretty easy with your cad program.

Check also the insulation distance between the screwholes and the supply planes. It's too tight according to my taste. Have you take the screw head into account?

Why don't you move all designators so you can see those even when the parts are there? It much easier to troubleshoot!

Picture here as an example. I have even drawn lines, check T10!
http://home5.swipnet.se/~w-50674/hif...r0_topview.jpg

You power supply has a but thin traces, 150 mil or even more! Route the trace to the capacitor and the route from, not add this short "inductance". It is proabaly nothing but check Joseph_K's measurements about the influence of unnecessary inductance.

carlosfm · 18th January 2005, 07:01 PM

?iginally posted by peranders [/i]
You shouldn't snubberize you design? Why don't you add 100 nF/63V polyester/ceramic + 1 ohms so Carlos will get happy? At least 100 nF would be good I think.[/QUOTE]

Why would I be happy?

Actually, it's time to talk about $$$$, if this is to be included in a commercial PCB.

Are you recommending the snubber now?

18th January 2005, 03:05 PM	#1
BrianGT diyAudio Moderator Emeritus Join Date: Jan 2002 Location: near Atlanta, GA	my first try at a LM3886 layout, any comments/suggestions? Here is my first try at an LM3886 layout. I have been sitting on this design for about 10 months now, and decided to put the last touchs on it last night. Let me know what you think. btw: I am still backlogged in mails, and will try to catch up soon. -- Brian

18th January 2005, 03:25 PM	#2
UrSv diyAudio Member Join Date: Jan 2002 Location: Sweden	Looks very good indeed. Can't wait to get myself a few of those. __________________ UrSv Those who say it can't be done should not stop those who are doing it.

18th January 2005, 04:58 PM	#6
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	You shouldn't snubberize you design? Why don't you add 100 nF/63V polyester/ceramic + 1 ohms so Carlos will get happy? At least 100 nF would be good I think. The grounding looks good! :up. __________________ /Per-Anders (my first name) or P-A as my friends call me

18th January 2005, 06:15 PM	#9
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	I think you should have this snubber close to the supply pins, not far away. I think also that the speaker trace is a bit thinn. Remember that you have at least 11 A worst case. I recommend a 150 mils trace. I would aslo recommend that you make a decent schematic. It must be pretty easy with your cad program. Check also the insulation distance between the screwholes and the supply planes. It's too tight according to my taste. Have you take the screw head into account? Why don't you move all designators so you can see those even when the parts are there? It much easier to troubleshoot! Picture here as an example. I have even drawn lines, check T10! http://home5.swipnet.se/~w-50674/hif...r0_topview.jpg You power supply has a but thin traces, 150 mil or even more! Route the trace to the capacitor and the route from, not add this short "inductance". It is proabaly nothing but check Joseph_K's measurements about the influence of unnecessary inductance. __________________ /Per-Anders (my first name) or P-A as my friends call me

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18th January 2005, 03:49 PM	#3
BrianGT diyAudio Moderator Emeritus Join Date: Jan 2002 Location: near Atlanta, GA	Thanks, With regards to the layout, has anyone tried adding the mute capacitor to the layout? Is this a recommended addition? The datasheet seems to like 100uF for this. I was thinking about possibly adding the cap to the layout, based on a suggestion I received. Also, would it make sense to add a jumper for allowing the mute functionality to be switched on and off? -- Brian

18th January 2005, 04:17 PM	#4
r!sc! Account Disabled Join Date: Jun 2003 Location: Serbia	Very nice Boban

18th January 2005, 04:26 PM	#5
BrianGT diyAudio Moderator Emeritus Join Date: Jan 2002 Location: near Atlanta, GA	Here is a version with the Cm cap added: Datasheet says: "Mute capacitance set up to create a large time constant for turn-on and turn-off muting." The value in the datasheet is 100uF, and this will be an optional component, as is the zobel network components. For using the larger BG capacitors, the cap can be omitted, or stuffed on the bottom of the pcb. -- Brian

18th January 2005, 07:01 PM	#10
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	?iginally posted by peranders [/i] You shouldn't snubberize you design? Why don't you add 100 nF/63V polyester/ceramic + 1 ohms so Carlos will get happy? At least 100 nF would be good I think.[/QUOTE] Why would I be happy? Actually, it's time to talk about $$$$, if this is to be included in a commercial PCB. Are you recommending the snubber now?

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