Output stage efficiency with varying rails voltage - diyAudio
 Output stage efficiency with varying rails voltage
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Solid State Talk all about solid state amplification.

 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
 9th December 2014, 05:43 AM #1 diyAudio Member   Join Date: Jul 2008 Output stage efficiency with varying rails voltage I am powering a class AB output stage from batteries, and the rail voltages will vary from +/-21V to +/-25V. The output must remain full amplitude and constant (as the supply decreases due to batteries getting slowly depleted) and the efficiency must be maximised at all times. In order to maximise efficiency the signal amplitude must be as close to the rails as the output stage will allow. But with varying rails from 21V to 25V, I have designed for the 21V, which means that when the batteries are fresh, 25V, then we have a lot of wasted power. Ideas for improving the situation: I was thinking of placing a DC-DC converter LM2596 at the batteries end, to provide a constant DC, say 20V, so then I can design for a fixed 20V. The DC-DC converter would be 80%-90% efficient and will not get too hot. not as much as the output stage would get if it were fed with 25V but used only 20V. PS: Sorry meant to say LM2679 Another idea that has been suggested is to use a class D output stage - except I have no knowledge of this and the immediate question is would it be efficient at full volume which is how my device works? Last edited by akis; 9th December 2014 at 06:05 AM.
 9th December 2014, 11:33 AM #2 diyAudio Member   Join Date: Jan 2009 Class D is the only way if you want something efficient and this explains it better than I can: Class-D Amplifiers Assuming you are playing music rather than a continuous waveform, your efficiency will be low. The article says less than 50%, but I would say less than 20% as music typically has more than 10dB dynamic range, so your average music signal will be at less than 10% power on the first graph on the page. Brian

 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 OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post akis Solid State 34 2nd December 2014 04:06 PM rhythmsandy Solid State 0 13th October 2013 06:03 PM phoenix87 Solid State 3 10th June 2010 07:02 AM Klimon Tubes / Valves 2 23rd May 2009 11:44 PM thylantyr Solid State 1 5th February 2004 07:11 AM

 New To Site? Need Help?

All times are GMT. The time now is 06:26 PM.