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

[danielwritesbac]

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]

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

 

[danielwritesbac]

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

 

[MJL21193]

Hi,
If you have MS Excel, you can work with the design spreadsheet here:http://www.national.com/appinfo/audio/files/Overture_Design_Guide15.xls

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

 

[danielwritesbac]

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.