LM4780 (LM3886) impedance issues - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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
Reply
 
Thread Tools Search this Thread
Old 21st November 2006, 11:33 AM   #1
diyAudio Member
 
Alfetta87's Avatar
 
Join Date: May 2003
Location: Alsace
Default LM4780 (LM3886) impedance issues

The national semiconductor datasheet doesn't say if the bridged (or parallel) application of the LM4780 would hold on with a 4 ohms load, even with its maixmum voltage used.

Has anybody got some experience with that?

Same for the LM3886 in brdiged mode.

Thanks,

- dan
__________________
It is worth to keep your mouth shut and let people think you’re stupid; rather than to open it and thus eliminate any doubts...
  Reply With Quote
Old 21st November 2006, 02:35 PM   #2
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
If you look at the "overture design tool" on National's website you can quickly determine the heat sink rating for a given rail voltage and impedance.

You can play around with the numbers and determine which heat sink/rail voltage combination is appropriate -- there's no need to guess.

I have used the LM4780 at higher PDMax than recommended by National by using forced air through the heat sink -- be mindful this causes the thermal protection to cycle on-and-off -- it's a nice experiment but something that you shouldn't try at home on your expensive speakers.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Using a lm4780 instead of 2x lm3886? nicku1302 Chip Amps 10 12th November 2007 02:36 AM
Switch impedance issues in Wallin 2 Jig Dave Bullet Multi-Way 9 28th May 2007 10:13 PM
MTM Impedance Issues matt09 Multi-Way 10 10th August 2006 03:13 PM
LM3886 & PGA2310 issues Xlrator Chip Amps 0 7th March 2006 07:25 AM
lm3886, lm4780, elementx Swap Meet 4 29th December 2005 02:44 AM


New To Site? Need Help?

All times are GMT. The time now is 06:51 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2