can we apply +ve and -ve voltages to a comparator if we operate the comparator in a s

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drkjreddy

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can we apply +ve and -ve voltages to a comparator if we operate it with single supply

I am haivng a doubt on using LF356/general op-Amp as a comparator.

I do believe that LF356 Op amp can be operated with dual mode supply +12v and -12V and single mode supply.suppose if I am operating the op amp in single supply mode, say with +12 volts and other pin is grounded to make a comparator.
Now in this case can we apply negative voltage to the inverting or inverting inputs if other pin is used as a reference input and applied +ve voltages. Kindly go throught the picture for more details

With thanks

kjreddy
 

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Why don't you refer to a LF356 datasheet? There is a specification called "Absolute maximum ratings". The datasheet tells explicitely
However, neither of the input voltages should be allowed to exceed the negative supply as this will cause large currents to flow which can result in a destroyed unit.
Click to expand...
I'm under the impression this is pretty clear.

Besides "Absolute Maximum Ratings" there's also a "Input Common-Mode Voltag Range". With LF356, the common mode range starts above 3 V above the negative supply voltage. In other words, the devices isn't suited for typical single supply applications.

P.S.: You won't hardly find an OP or comparator, that can accept input voltages more than a few 100 mV below the negative supply rail.
 

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