Voltage spike when using LM1117

[Kasper111]

Hi,

I am trying to make a DC/DC converter with a LM1117 which convert 11V to 9V. I am using a system example from the datasheet. 

So my question is. What causing the voltage spike when switching from "ON" to "OFF" at the switch "S1"

Datasheet: http://www.ti.com/lit/ds/symlink/lm1117.pdf

[ikaiser]

Hello Kasper,

Would you please be so kind to attach your actual MultiSim file? This lowers the threshold to play around with our issue by far, as re-creating the schematics from the screenshot it work...