What's a normal temp for LM3886 on 40+40 DC?

danielwritesbac · 22nd January 2008, 01:52 AM

Hi, I was wondering what thermals I should expect from LM3886 on voltage like 40+40 DC?

Howabout when running 4 ohm speakers at full tilt?

What temperatures would you expect?

MJL21193 · 22nd January 2008, 01:55 AM

Should NOT run this chip at 40 volt rails into 4 ohm load. Might get away with 8 ohms.

danielwritesbac · 22nd January 2008, 02:35 AM

Have you tried that? If so, what was your experience with the heatsink requirements?

MJL21193 · 22nd January 2008, 02:44 AM

Hi,
If you have MS Excel, you can work with the design spreadsheet here:http://www.national.com/appinfo/audi...gn_Guide15.xls

The recommended power supply for 8 ohms is +/-35 volts. To go with higher rail voltage could trigger the SPIKE protection.

danielwritesbac · 22nd January 2008, 06:51 AM

Thank you!!!
The last copy of that spreadsheet that I had didn't work.
Yours worked like a charm.
It also answered my NFB puzzle on how to get some serious headroom without going off spec.

22nd January 2008, 01:52 AM	#1
danielwritesbac diyAudio Member Join Date: Nov 2007	What's a normal temp for LM3886 on 40+40 DC? Hi, I was wondering what thermals I should expect from LM3886 on voltage like 40+40 DC? Howabout when running 4 ohm speakers at full tilt? What temperatures would you expect? __________________ ClipNipper--trim the clipping not the audio.

22nd January 2008, 02:35 AM	#3
danielwritesbac diyAudio Member Join Date: Nov 2007	Have you tried that? If so, what was your experience with the heatsink requirements? __________________ ClipNipper--trim the clipping not the audio.

22nd January 2008, 06:51 AM	#5
danielwritesbac diyAudio Member Join Date: Nov 2007	Thank you!!! The last copy of that spreadsheet that I had didn't work. Yours worked like a charm. It also answered my NFB puzzle on how to get some serious headroom without going off spec. __________________ ClipNipper--trim the clipping not the audio.

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22nd January 2008, 01:55 AM	#2
MJL21193 Account disabled at member's request Join Date: Mar 2007	Should NOT run this chip at 40 volt rails into 4 ohm load. Might get away with 8 ohms.

22nd January 2008, 02:44 AM	#4
MJL21193 Account disabled at member's request Join Date: Mar 2007	Hi, If you have MS Excel, you can work with the design spreadsheet here:http://www.national.com/appinfo/audi...gn_Guide15.xls The recommended power supply for 8 ohms is +/-35 volts. To go with higher rail voltage could trigger the SPIKE protection.

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