Op amp output when one supply is not connected

[hithesh123]

What is the output of the op amp when either Vcc or Vee is not connected.
I simulated this and got Vsat. +Vsat when Vee was missing and -Vsat when Vcc was missing.
But I don't know why the output saturates to +Vsat, even in a inverting configuration. Shouldn't it go to ground, since the output equation is Vout = -Rf/R1 (Vin)
Same output as above, when Vin is zero. Op amp in question is TLE2061
Can some one tell me from the equivalent diagram in the datasheet, which transistors will be turned ON at the output stage?

 

[keith1200rs]

You cannot usually simulate it with the models from the opamp manufacturers. They provide models for a particular set of circumstances, one of which will be the power being connected. If you have a transistor level model of the complete opamp then such a simulation would make sense.

Keith.

 

[FvM]

Most likely, the OP output turns on (or even saturates), because the device gets a "parasitic" power supply through input pins and substrate diodes. So for a clear question, please tell the voltage levels at all connected pins. This applies to the real device.

A simulation must not necessarily behave identical to the real device in irregular operation conditions (but it can, of course). In this case, you should refer to the simulation model rather than the datasheet circuit.

 

[hithesh123]

Vcc is +5V, Vee is -5V
Input is 0v.
Non inverting configuration.

 

[FvM]

The real OP will get parasitic power supply, if one of both input has a low impedance ground connection. This operation isn't correctly modelled in ususal TLE2061 SPICE macro models.