Electronic – Why does this single supply non inverting Op-Amp saturate

dcoperational-amplifiersingle-supply-op-amp

I have this simple non inverting setup made with a TL082IP Op-Amp and a gain set to 2 (R1 = R2). Since I will only have positive voltage 0V to 5V to amplify, I use for simplicity a single 12V/0V supply voltage (V2).

schematic

simulate this circuit – Schematic created using CircuitLab

If I vary the V+ voltage source between 0V and 5V (V1), I would expect Vout varying between 0 and 10V, which is what the simulation give me.

But in practice, everything works fine between 5V and ~0.8V, then between 0.8V and 0V the Op-Amp saturates at +Vsat ~12V.

What have I missed ? I don't really need precision at low voltage, but at least I would like that low voltage at V+ give me low voltage at Vout, how could I achieve this ?

Thank you !

Best Answer

Look at this extract from the TL082 data sheet and learn: -

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The input signal is invalid if it gets close to the negative rail (within 3 volts). The negative rail is 0 volts in your circuit hence anything below +3 volts is likely to be problematic.