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OPAMP as single supply

Nbj123

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Hello,

It is possible to use OPAMP as a single supply and get negative output from it.
In my circuit I am giving a 7-15V supply and want to negative output.
Please guide.

Thanks
 

betwixt

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An op-amp can't produce an output voltage outside the range you supply it with. You might be able to create a virtual ground using an op-amp, where the output pin is used as ground and the supply sits either side of it but there are limitations to the current it could provide and the combined positive and negative sides will not be greater than the supply.

Brian.
 

KlausST

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Hi,

Since an Opamp has no GND pin .. it always is "single supplied".
But even manufacturers and datasheets refer to "single supplied" when the negative supply is connected to GND.

Now to your question:
--> The (driven) output voltage of an Opamp is always within it's supply rails.
Opamps with output going close (within millivolts) to the supply rails are called "rail to rail output"

But every Opamp that is specified for 5V supply may be supplied with:
* 0V / 5V
* 5V / 10V
* -5V / 0V
* -100V / -95V
* 100V / 105V
Just the difference counts.
And all inputs and outputs refer to these supply rails.

It's essential to read datasheets.

Klaus
 

danadakk

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There are OpAmps than can deliver bipolar output from a
single power supply (onchip charge pump to create - supply) -


Keep in mind you can always use a switcher or a charge pump IC to gen
negative V's to run split supply designs....The above part just happens to have
that built into it with its two opamps internal as well.


Regards, Dana.
 
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