Ravaner
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Hello. I'm looking for a quad op amp similar to TL074 but rail to rail (mainly for input) in DIP14 (I found a lot in SMD) and supporting +12V / -12V as power supply.
The forum discussion centers on finding a quad rail-to-rail operational amplifier (op amp) in a DIP14 package, similar to the TL074, that operates with a ±12V power supply. Users suggest several alternatives, including the Texas Instruments LMC6484 and LT1491, while noting limitations in speed and package type. The conversation also explores potential solutions like using MOSFETs for pre-amplification and the possibility of using SMD to DIP adapters for compatibility. Key insights include the challenges of achieving rail-to-rail input in bipolar technology and suggestions for voltage dividers to maintain common mode range.
PREREQUISITESElectronics engineers, circuit designers, and hobbyists seeking to implement rail-to-rail operational amplifiers in their projects, particularly those requiring DIP14 packages.
Google found http://cds.linear.com/docs/en/datasheet/16789fs.pdfRavaner said:Hello. I'm looking for a quad op amp similar to TL074 but rail to rail (mainly for input) in DIP14 (I found a lot in SMD) and supporting +12V / -12V as power supply.
OOPS !Ravaner said:Thanks but I'm looking for DIP14 package not SMD
Adapters are available to do the conversion.Ravaner said:Thanks but I'm looking for DIP14 package not SMD
I don't think there is such a thing, at least not in bi-polar technology. Consider that the input stage will have an inherent VBE to turn on and that there must be a load for the first stage, in either the Emitter or Collector, to sense the change in current. It might be possible in MOSFET technology with a depletion mode input stage but I haven't thought it through completely. Your best bet is to put a voltage divider in the input to stay within the Common Mode range. You only need to lose 10% to 20% of input range, not a big hit for later gain stages.Ravaner said:rail to rail (mainly for input)
Ravaner said:looking for a quad op amp similar to TL074 but rail to rail (mainly for input)
Tom.G said:FURTHER DIGGING:
You may be able to use a couple of MOSFETs as a pre-amp input stage to get close to rail-to-rail input but it seems like a lot of added complexity for little gain.
A Google search shows a few hits for rail-to-rail input but they are low supply voltage (7V), single or dual, and small packages.
https://www.google.com/search?q="op+amp"+depletion+mode+input
CWatters said:I see someone already suggested adaptors.
Tom.G said:I don't think there is such a thing, at least not in bi-polar technology. Consider that the input stage will have an inherent VBE to turn on and that there must be a load for the first stage, in either the Emitter or Collector, to sense the change in current. It might be possible in MOSFET technology with a depletion mode input stage but I haven't thought it through completely. Your best bet is to put a voltage divider in the input to stay within the Common Mode range. You only need to lose 10% to 20% of input range, not a big hit for later gain stages.
Interesting approach! I'm interesting in following up on it. Can you point me to a datasheet so I can follow up?analogdesign said:The key idea is to put a PNP diff pair in parallel with a NPN diff pair.