Differential opamp output clipping

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sabu31

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I am using differential opam to sense AC voltage. When I give Vcc as 3.3V, and dc bias as 1.65V. The system is clipping even if the output does not reach the full 3.3V range (by changing the feedback resistors).
However, when I am using Vcc as 5V there is no issue. What could be the reason for this. The opamp used is TLC2272.
 

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I get the following as sim :




Is the 400 V input galvanically isolated from the TLC2272 ground ?

Notice design violating input CM range ( 5V supply ) :



Notice design violating input CM range (and below is only typical) :



Notice when I change supply to 3V, a 10% drop, the onset of clipping :



A 5V supply to the OpAmp might make sense. Especially in terms of margins, T and V. Or a R-R
I/O OpAmp, this one includes - rail but not + rail.


Regards, Dana.
 
Last edited:

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sabu31 said:
400V is not galvaniccally isolated.
Click to expand...
so, then how is it "referenced" to your system GND?

******
Clipping:
Simple tests:
Use a scope and measure:
* voltage at IN+
* voltage at IN-
* voltage at OUT
(just as Dana did. It tells everything ... in combination with your schematic informations and the datsheet)

You tell us "it clips" but we don´t see it ... don´t let us guess

Klaus
 

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Minimal TLC2272 supply voltage according to datasheet is +/- 2.2V, respectively 4.4V single supply. More questions?
 

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    sabu31

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