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TINA/Spice/OPA859: Weird behaviour of output during power down

Emmanouil Tsachalidis
Intellectual 850 points
Part Number: OPA859
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hi,

I was trying to confirm the impedance of the OPA859 during a power down condition. It turns out that the "high impedance" stated in the datasheet (p19 at the bottom) is not followed by the spice model.

See the pics below:

The following is the output during normal operation where the +IN is grounded and the output level is defined by the input offset.

This is the condition where power down condition is in effect and the output level should be defined by the divider network formed by output impedance and the 1k resistor.

Instead, the output impedance seems to be extremely low thus pushing the voltage drop across opamp's output down to 50mV.

Now, if i completely disconnect the power rails of the opamp i get this:

Is this a bug of the spice model? Am i doing anything wrong here?

OPA859 - PD status VS output impedance.TSC

Regards

Manos Tsachalidis