Opamp on battery - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 4th May 2016, 03:14 AM   #1
diyAudio Member
 
Join Date: Jul 2015
Default Opamp on battery

Hello,
I am building a dac that is battery based until now. Now i am at the iv stage and would like to use the lme49990 opams, because i like their neutral sound.
Now my question : the lme49990 needs a positive and negative voltage, but i only have positive voltages on battery. Is there a way to generate a nehative voltage out of a battery or will i need to skip the lme49990 and choose a single voltage opamp ? Is there any single voltage opamp comparable to the lme49990 ?

Thanks
Tom
  Reply With Quote
Old 4th May 2016, 03:40 AM   #2
diyAudio Member
 
Join Date: Jul 2013
Use two batteries? Also keep in mind the high idle current of the LME49990 - it's around 10mA each at high voltages. This is probably one of the reasons why it performs so well, but still, for a battery supply, keep this high idle current in mind. And, don't starve it for voltage. It works very well at 17V supplies. (Note - this is the same thing as a 34V single supply as long as you get the inputs to be within the permissible input common mode voltage range.)

Or, one could simply design an effective power supply...?
  Reply With Quote
Old 4th May 2016, 03:48 AM   #3
jstott is offline jstott  United States
diyAudio Member
 
Join Date: Feb 2016
Location: Connecticut
As already mentioned, a pair of 9V batteries would be one option. Another possibility is an iC called a "rail splitter" (the TLE2426 is a good example). Their capacity to sink/source current is limited, but if it's just an opamp or two you should be fine.
  Reply With Quote
Old 4th May 2016, 08:44 PM   #4
diyAudio Member
 
Join Date: Jul 2015
Rhanks for the help. The rail splitter is an option. Does it introduce much noise to the negative rail ?
The 10mA at idle are no problem. I use two 8ah lifepo4 batteries for 6,4v. Does the lme49990 behave much better at higher voltages ? I can give it +/-6V and not more at the moment. I read somewhere that it runs fine from 5V upwards. Is that right ?
  Reply With Quote
Old 4th May 2016, 08:50 PM   #5
diyAudio Member
 
Join Date: Jul 2015
Ok, tle2426 generates a virtual ground and v/2 + and - voltage. This would mean 4 batteries for me. What about a chargepump like the max660 ? Would this function ?
  Reply With Quote
Old 5th May 2016, 09:29 AM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Gone on holiday again. back soon.
AC couple the opamp and operate it from a single supply.
__________________
regards Andrew T.
Sent from my desktop computer using a keyboard
  Reply With Quote
Old 5th May 2016, 01:10 PM   #7
diyAudio Member
 
Join Date: Jul 2015
Quote:
Originally Posted by AndrewT View Post
AC couple the opamp and operate it from a single supply.
Its a mobile design, i dont have any AC voltage, only batteries at 6.4V.

Nobody has an Idea ?
  Reply With Quote
Old 5th May 2016, 01:24 PM   #8
marce is offline marce  United Kingdom
Heretic
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs


http://www.ti.com/lit/an/sboa059/sboa059.pdf

Last edited by marce; 5th May 2016 at 01:27 PM.
  Reply With Quote
Old 5th May 2016, 01:34 PM   #9
diyAudio Member
 
Join Date: Jul 2015
Thanks. Now i understand. Thats an option of course.
I am also reading about passive IVs at the moment. What does sound better ? Opamp or passive IV ? Passive IV could make my problems go away.
  Reply With Quote
Old 6th May 2016, 02:34 AM   #10
diyAudio Member
 
Join Date: Jul 2013
The data sheet specifies the LME49990 at 5V, and the distortion plots look very close to those for 15V, except for the output voltage swing of course. The output swing will be somewhat reduced, since it's not a rail-to-rail amplifier, but there is no rail-to-rail amp that can give you the same level of performance. So, a pair of 6.4V batteries should work well, and you avoid the hassles of a rail splitter or other AC coupling / biasing schemes.
  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
Battery powered phono stage battery type advice Hikari1 Analogue Source 5 10th September 2013 10:00 PM
PGA2310 - PGA2311 - CS3310: version without OPAMP for outdoor OPAmp connection wanted tiefbassuebertr Analog Line Level 11 9th July 2013 06:50 AM
Decoupling for battery based opamp circuits diy didi Solid State 3 6th December 2012 07:06 PM
Battery Charger for 15V Li-ION Battery Pack ??? Jan Dupont Parts 2 11th April 2009 03:18 PM
Single supply opamp - unequal rail voltage and opamp selection Hans L Parts 8 19th February 2006 03:15 PM


New To Site? Need Help?

All times are GMT. The time now is 03:07 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki