plz help abt these opamp basics

[beedee]

why LM 324 is used as in "opamp as an amplifier" and not as "opamp as a comparator"
As well as why LM 339 is used as in "opamp as an comparator" and not as "opamp as a amplifier"
when in fact opamp can be used in both configurations..why the need to use thes ICs for specific purpose only.

 

[maziaar83]

High input impedance and large open loop voltage gain make an op-amo perfectly suitable for comparator applications. but...

Comprator Characteristics:
a)Speed of Operation
b)Accuracy
c)Compatibility of output

In some applications they are not important but in precision applications op-amp should have: 1. positive feedback for improving speed and avoiding false transition due to noise 2. offset voltage compensating network and offset minimizing resistor 3. It should be compatible with some logic family.

Don't forget to push "Helped Me" button

 

[rfzheng]

the basic dircrimination of OPAMP and Comparator is that OPAMP nornally used in closed loop, but comparator in open loop.

so, opamp has to consider the stability problem, and in order to simplify the useage of the opamp ,designer will design compensation network in the chip. But some opamp has not internal compensation network ,it need external compensation. this kind of opamp is also can be used as a comparator if you do not compensated it when you use it as a comparator.
if you want to use it as a opamp ,you normally should compensate it.
so this kind of opamp has some kind of general-purpose.

I do not know if you have get your answer.

 

[beedee]

i think i confused all in my question.
actually what i wanted to know is
why LM339 is used only as comparator and not for amplification or inversion
and why LM324 is used for amplification and not comparision..
if ne1 cud hlp me fast it wud b hlpful bcoz i hav an interview on it day after tomorrow