Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 21st April 2008, 02:59 AM   #1
kkchunghk is offline kkchunghk  Hong Kong
diyAudio Member
Join Date: Oct 2004
Default Lm4950

Has anyone used LM4950 in stereo mode? The data sheet shows a value of 470uF for Cout. Is this a misprint or what? After a quick search at Farnell, 100uF bi-polar electrolytic is the highest availabe. Strangely there is no Cout in mono mode. I would have thought a 10uF is sufficient for decoupling the chip from the speakers. Any suggestions.
  Reply With Quote
Old 21st April 2008, 09:24 AM   #2
boholm is offline boholm  Denmark
diyAudio Member
boholm's Avatar
Join Date: Apr 2004
Location: Copenhagen
Default Re: Lm4950

I haven't tried it at all. But i can read in the pdf that it is intended for sound in flat panels.

470 F for Cout is adequate, since it is not intended to give deep bass. Lower frequency limit calculated to 86 Hz. The circuit on p4 of the National pdf has only an amplification of 1 => a buffer and a voltage swing of max. +/- 9 volts - in bridged mode +/- 18.

A 10 F for decoupling sufficient? Sorry, but I don't understand . . . ?

What do you wish to use it for?
Best regards
  Reply With Quote
Old 21st April 2008, 06:57 PM   #3
kikikaka is offline kikikaka  Hungary
diyAudio Member
Join Date: Mar 2006
Location: Budapest
Both amplifiers' output are biased to Vdd / 2 in idle, so this is a typical chip of one-supply solutions.

For the stereo amplifier you DO NOT need bi-polar capacitor on the output. Cout should be a normal electrolytic capacitor, 470 or 1000uF (maybe paralell with a n*100nF ceramic capacitor).

BUT! Cin must be definitely bi-polar, maybe a ceramic one.

Yes, there's no Cout in the mono application, because the two amplifiers working in bridged mode, with 180 degrees phase shifting... (with no output half Vdd should be measured on both pins of the speaker)

  Reply With Quote
Old 23rd April 2008, 07:42 AM   #4
kkchunghk is offline kkchunghk  Hong Kong
diyAudio Member
Join Date: Oct 2004
Thank you guys.
  Reply With Quote


Lm4950Hide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Oscillation in LM4950 Design rswilson Chip Amps 0 16th August 2004 12:53 AM

New To Site? Need Help?

All times are GMT. The time now is 05:05 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio