LM339 Question (Beau Schwabe)
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Beau, The circuit that I an doing is the National AN-453, you know
the AIC. well do you think I can use the LM324 for the circuit on
page 4? or will I have to add a diode?
TC
--- In basicstamps@y..., "Beau Schwabe" <bschwabe@a...> wrote:
> At 09:24 PM 5/3/01 +0000, you wrote:
> >Hello all,
> >
> >Dose any one know if I can use A LM324 inplace of a LM339 for a
> >project? The sheat that I got says to use a LM339, well I got a
LM324
> >that I had laying around.
> >
> >please help
> >TC
>
> The short answer to your question is YES because you are using an
> Op-Amp in-place of a Comparator. If you were using a Comparator
> in-place of an Op-Amp, I would be more hesitant to say YES.
> ...your circuit however might require a diode on the output on
> each Comparator...
>
> Old Output >
|<----> New Output
>
> ...The diode allows the remainder of the circuit to "think" that
> it has the "open-collector" outputs on the OP-Amp (LM324) that
> would typically be on a Comparator. (See below) ...although it
> is possible that the circuit doesn't care either way, you may not
> even need the diodes.
>
> Your question is more of an application dependent question...
> The most substantial difference between a Comparator (LM339) and
> an Op-Amp (LM324) is that the Comparator is Open Collector, meaning
> that it is never driven HIGH.
>
> In most circuits where a Comparator is used, it might be ok to
> substitute an Op-Amp.
>
> On the other hand, in circuits where an Op-Amp is used, it is
> unlikely that a Comparator could be used as easily. But again, this
> mainly depends on the application.
>
> See: http://www.national.com/pf/LM/ for a list of datasheets....
>
>
> ...under the LM339, take a look at page 15 and compare that
> schematic to the LM741 page 4, and see how much they differ.
> The Op-Amp is driven both HIGH and LOW, while the Comparator
> is only driven LOW.
>
>
>
>
>
> Beau Schwabe IC Mask Designer
> National Semiconductor Wired Communications Division
> 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>
the AIC. well do you think I can use the LM324 for the circuit on
page 4? or will I have to add a diode?
TC
--- In basicstamps@y..., "Beau Schwabe" <bschwabe@a...> wrote:
> At 09:24 PM 5/3/01 +0000, you wrote:
> >Hello all,
> >
> >Dose any one know if I can use A LM324 inplace of a LM339 for a
> >project? The sheat that I got says to use a LM339, well I got a
LM324
> >that I had laying around.
> >
> >please help
> >TC
>
> The short answer to your question is YES because you are using an
> Op-Amp in-place of a Comparator. If you were using a Comparator
> in-place of an Op-Amp, I would be more hesitant to say YES.
> ...your circuit however might require a diode on the output on
> each Comparator...
>
> Old Output >
|<----> New Output
>
> ...The diode allows the remainder of the circuit to "think" that
> it has the "open-collector" outputs on the OP-Amp (LM324) that
> would typically be on a Comparator. (See below) ...although it
> is possible that the circuit doesn't care either way, you may not
> even need the diodes.
>
> Your question is more of an application dependent question...
> The most substantial difference between a Comparator (LM339) and
> an Op-Amp (LM324) is that the Comparator is Open Collector, meaning
> that it is never driven HIGH.
>
> In most circuits where a Comparator is used, it might be ok to
> substitute an Op-Amp.
>
> On the other hand, in circuits where an Op-Amp is used, it is
> unlikely that a Comparator could be used as easily. But again, this
> mainly depends on the application.
>
> See: http://www.national.com/pf/LM/ for a list of datasheets....
>
>
> ...under the LM339, take a look at page 15 and compare that
> schematic to the LM741 page 4, and see how much they differ.
> The Op-Amp is driven both HIGH and LOW, while the Comparator
> is only driven LOW.
>
>
>
>
>
> Beau Schwabe IC Mask Designer
> National Semiconductor Wired Communications Division
> 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>
Comments
a LM324.... I would use the diodes because of the 3.3K pull-up
resistors in the schematic, and because I don't know what kind
of currents the COP452's and COP444L are expecting. The 3.3K at
least limits this to about 1.5mA of current. The LM339 in this
circuit functions more as a buffer to the remainder of the circuit.
BTW) Any reason you don't want to spend $2 on a LM324?
>Beau, The circuit that I an doing is the National AN-453, you know
>the AIC. well do you think I can use the LM324 for the circuit on
>page 4? or will I have to add a diode?
>
>TC
>
>
>--- In basicstamps@y..., "Beau Schwabe" <bschwabe@a...> wrote:
> > At 09:24 PM 5/3/01 +0000, you wrote:
> > >Hello all,
> > >
> > >Dose any one know if I can use A LM324 inplace of a LM339 for a
> > >project? The sheat that I got says to use a LM339, well I got a
>LM324
> > >that I had laying around.
> > >
> > >please help
> > >TC
> >
> > The short answer to your question is YES because you are using an
> > Op-Amp in-place of a Comparator. If you were using a Comparator
> > in-place of an Op-Amp, I would be more hesitant to say YES.
> > ...your circuit however might require a diode on the output on
> > each Comparator...
> >
> > Old Output >
|<----> New Output
> >
> > ...The diode allows the remainder of the circuit to "think" that
> > it has the "open-collector" outputs on the OP-Amp (LM324) that
> > would typically be on a Comparator. (See below) ...although it
> > is possible that the circuit doesn't care either way, you may not
> > even need the diodes.
> >
> > Your question is more of an application dependent question...
> > The most substantial difference between a Comparator (LM339) and
> > an Op-Amp (LM324) is that the Comparator is Open Collector, meaning
> > that it is never driven HIGH.
> >
> > In most circuits where a Comparator is used, it might be ok to
> > substitute an Op-Amp.
> >
> > On the other hand, in circuits where an Op-Amp is used, it is
> > unlikely that a Comparator could be used as easily. But again, this
> > mainly depends on the application.
> >
> > See: http://www.national.com/pf/LM/ for a list of datasheets....
> >
> >
> > ...under the LM339, take a look at page 15 and compare that
> > schematic to the LM741 page 4, and see how much they differ.
> > The Op-Amp is driven both HIGH and LOW, while the Comparator
> > is only driven LOW.
> >
> >
> >
> >
> >
> > Beau Schwabe IC Mask Designer
> > National Semiconductor Wired Communications Division
> > 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
> >
>
>
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Beau Schwabe IC Mask Designer
National Semiconductor Wired Communications Division
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
around. But, Thanks for your help
TC
--- In basicstamps@y..., "Beau Schwabe" <bschwabe@a...> wrote:
> Looking at the schematic, it would probably be ok to substitute
> a LM324.... I would use the diodes because of the 3.3K pull-up
> resistors in the schematic, and because I don't know what kind
> of currents the COP452's and COP444L are expecting. The 3.3K at
> least limits this to about 1.5mA of current. The LM339 in this
> circuit functions more as a buffer to the remainder of the circuit.
>
> BTW) Any reason you don't want to spend $2 on a LM324?
>
>
> >Beau, The circuit that I an doing is the National AN-453, you know
> >the AIC. well do you think I can use the LM324 for the circuit on
> >page 4? or will I have to add a diode?
> >
> >TC
> >
> >
> >--- In basicstamps@y..., "Beau Schwabe" <bschwabe@a...> wrote:
> > > At 09:24 PM 5/3/01 +0000, you wrote:
> > > >Hello all,
> > > >
> > > >Dose any one know if I can use A LM324 inplace of a LM339 for a
> > > >project? The sheat that I got says to use a LM339, well I got a
> >LM324
> > > >that I had laying around.
> > > >
> > > >please help
> > > >TC
> > >
> > > The short answer to your question is YES because you are using
an
> > > Op-Amp in-place of a Comparator. If you were using a Comparator
> > > in-place of an Op-Amp, I would be more hesitant to say YES.
> > > ...your circuit however might require a diode on the output on
> > > each Comparator...
> > >
> > > Old Output >
|<----> New Output
> > >
> > > ...The diode allows the remainder of the circuit to "think" that
> > > it has the "open-collector" outputs on the OP-Amp (LM324) that
> > > would typically be on a Comparator. (See below) ...although it
> > > is possible that the circuit doesn't care either way, you may
not
> > > even need the diodes.
> > >
> > > Your question is more of an application dependent question...
> > > The most substantial difference between a Comparator (LM339) and
> > > an Op-Amp (LM324) is that the Comparator is Open Collector,
meaning
> > > that it is never driven HIGH.
> > >
> > > In most circuits where a Comparator is used, it might be ok to
> > > substitute an Op-Amp.
> > >
> > > On the other hand, in circuits where an Op-Amp is used, it is
> > > unlikely that a Comparator could be used as easily. But again,
this
> > > mainly depends on the application.
> > >
> > > See: http://www.national.com/pf/LM/ for a list of datasheets....
> > >
> > >
> > > ...under the LM339, take a look at page 15 and compare
that
> > > schematic to the LM741 page 4, and see how much they
differ.
> > > The Op-Amp is driven both HIGH and LOW, while the
Comparator
> > > is only driven LOW.
> > >
> > >
> > >
> > >
> > >
--
> > > Beau Schwabe IC Mask Designer
> > > National Semiconductor Wired Communications Division
> > > 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA
30071
> > >
--
> >
> >
> >
> >
> >Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
>
> Beau Schwabe IC Mask Designer
> National Semiconductor Wired Communications Division
> 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>