Single supply Op-amp

Discussion in 'General Electronics Chat' started by BillO, Jan 15, 2011.

  1. BillO

    Thread Starter Well-Known Member

    Nov 24, 2008
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    I'm a little out of the mainstream these days so please excuse what might be an obvious question to those that are up to date.

    What is the de facto standard for a single supply op-amp these days?

    Something that will run off a 9v battery. Low noise and low distortion are desirable (of course, but in reason). The application is in audio. 8 pin dip preferred.
     
  2. tom66

    Senior Member

    May 9, 2009
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    The LM324/358 will go down to ground within about 15mV, which is "good enough" for most applications. It's limited to 1.5V below the V+ rail, but again - with a 9V supply a 7.5V swing should be fine, especially for audio. The 358 is a dual op-amp available in DIP8 and the 324 is a quad op-amp in DIP14.
     
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  3. BillO

    Thread Starter Well-Known Member

    Nov 24, 2008
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    Perfect. Thanks Tom, will check it out.:)
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I'm a big fan of the TL0xx series, I mostly use the 82's and 84's however the 72 or 74 will have a little bit tighter specs. All are inexpensive, reliable and available about everywhere. Just an example:

    http://focus.ti.com/lit/ds/symlink/tl082.pdf

    If you want the best rail-rail drill down through the database at http://www.mouser.com

    My guess is you can buy a TL082 at a local Radio Shack: http://www.radioshack.com/product/index.jsp?productId=2062594&filterName=Type&filterValue=IC-Analog

    I assume you have those in Canada? If not there are many suppliers up there, just ask.
     
    Last edited: Jan 15, 2011
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  5. BillO

    Thread Starter Well-Known Member

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    Thanks Marshal.
     
  6. tom66

    Senior Member

    May 9, 2009
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    I don't think the 082/084's are rail-to-rail or even go down to ground; datasheet says output voltage swing is ±13.5V typically from a ±15V supply. At college, we use them here, and we always use them with ±15V supply and they manage about ±14V.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Actually, the TL07x/TL08x series have a common mode of -V +3v to +V -1.5v, so they're not that great for single-supply usage. The TL08x is a TL07x that didn't meet noise specifications.

    The LM324 and LM358 are pretty "long in the tooth"; there are LOTS of far more modern opamps out there nowadays.

    Take a look at the MC33078 dual opamp. It's not rail-to-rail, but is quieter, better GBW and requires less power than the TL07x series. http://www.onsemi.com/PowerSolutions/product.do?id=MC33078

    You could also look at an LM6132. http://www.national.com/mpf/LM/LM6132.html

    If you want something REALLY low noise, look at an LT1115: http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1154,C1009,C1026,P1293

    Do you already have a circuit in mind?
     
  8. tom66

    Senior Member

    May 9, 2009
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    That's not necessarily a bad thing. The 358/324 are cheap, commodity chips available from many suppliers, there are many applications for it on the 'net and in print and the design and its limitations are well know.
     
  9. BillO

    Thread Starter Well-Known Member

    Nov 24, 2008
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    Not really, just the concept, but it's nothing complicated.

    Just a simple inverting pre-amp stage for a headphone amplifier feeding into the tone, volume and over-drive controls. Over-drive will be handled with a couple of diodes. Output will be an LM386.

    Large output swing is not required.
     
  10. Audioguru

    New Member

    Dec 20, 2007
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    They are horrible for audio. They were the very first "low power" opamps so their output did not have proper bias current and produced awful crossover distortion.
    The low power reduced the max output frequency to only 2kHz at high levels. They produced a lot of hiss.

    I have used the TL071 single opamp, TL072 dual opamp and TL074 quad opamp for many years in audio circuits. They are low noise, have distortion that is only 0.003% and work at full output to 100kHz. They have Jfet inputs so have almost no input bias current. Their minimum supply is 7V. They are inexpensive.
     
  11. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I rarely use rail-rail, very few op-amps will unless they've got extremely low Rdss output stages as in MOSFETs and then you've got to keep withing the current requirements. Too little and they won't ground, too much and they won't either. Audio doesn't really require much more than a 17 Hz - 22 KHz (25-17K or lower if you're older) response unless you're superhuman or something and when operating off a single supply you're going to want an output cap in there anyway.

    The TL series is a workhorse, I use them to drive logic and all sorts of other things. Inexpensive as heck if you order them directly instead of from Ripoff-Shack so I just keep an assortment of them around as they even make fairly decent comparators. I've found the TI versions to be the best compared to the STM ones even if they may cost a few cents more.

    Guru, you're probably correct about hand picked as far as the 07 vs 08 but of course it would be machine done as the wafer full of dies comes out. How many of us could ever hear the difference unless it was at the very front end?

    All in all they're here to stay as are those stupid 741s which I see RS is still selling as too many project books still specify them.
     
  12. BillO

    Thread Starter Well-Known Member

    Nov 24, 2008
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    I can get the TL072 for 30 cents each in a lot of 20. For some reason they are more prevelant and less expensive than TL071, TL081 and TL082. Anyway, for $6 including shipping, I'll add 20 to my stock and give them a try.

    The MC33078 seems to be designed to use a dual supply, no?
     
  13. bertus

    Administrator

    Apr 5, 2008
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  14. SgtWookie

    Expert

    Jul 17, 2007
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    You can use a dual-supply opamp with a single supply; just isolate the DC level with a cap and bias the input at ~1/2 Vcc. You also need to isolate the output DC level. You'll need to do that whether you use a single or dual supply opamp, otherwise you'll clip the negative-going portion of the input signal.

    Both the TL072 and the MC33078 are dual-supply opamps; however the MC33078 has lower noise, a wider common range, wider output range, and nearly 4x the bandwidth of the TL07x series. They're more expensive at ~$1/ea:
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-1953-5-ND
    http://www.mouser.com/ProductDetail...GAEpiMZZMtCHixnSjNA6FBv1NGQXAA%2bmJB01QMhYM8=
    Mouser's 25 @ $0.67/ea deal isn't bad.

    Jameco stocks a ST Microelectronics version in SMT for $0.39/ea, 10 minimum:
    http://www.jameco.com/webapp/wcs/st...ecoall&ddkey=http:ParametricSearchResultsView
     
  15. t06afre

    AAC Fanatic!

    May 11, 2009
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    The Lm324 datasheet, also have a lot of circuits ideas. As said before the LM324 is perhaps not the best option in the marked. But you may still use the circuits ideas with other single supply opamps
    http://www.national.com/ds/LM/LM124.pdf
     
  16. Audioguru

    New Member

    Dec 20, 2007
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    They are a dual audio opamp so are used in millions of stereo audio products.
    There are not many mono or quad audio products made anymore.

    Any opamp works perfectly from a single polarity supply if its input is biased at half the supply voltage and a few coupling capacitors block the DC.
    The MC33078 dual opamp and MC33079 quad opamp are good audio opamps.
    They have low noise, low distortion and a full output swing to 120kHz.
     
  17. BillO

    Thread Starter Well-Known Member

    Nov 24, 2008
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    Thanks Guy's, you've given me a lot to work with.

    My last work with op-amps was with 741's back when they were the best you could do. Things have come a long way since the '70s.
     
  18. Wendy

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  19. Audioguru

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    You don't need a Virtual Power Supply Ground circuit for most opamps on a single polarity supply because the input bias current is extremely low. Two series 100k resistors with a filter capacitor to ground are all that is needed.
     
  20. Wendy

    Moderator

    Mar 24, 2008
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    I've been know to use that. I've also been known to bring the virtual ground out as a ground too. All depends on application.
     
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