Calculate max voltage of toggled inductor

[Hybird]

I have an inductor of 500uH that is attached to a 1volt source and the other side is connected to a mosfet RDSon = 0.012 ohm. If I turn on the mosfet for 5us and let current start to flow through the inductor I can calculate the max current reached assuming the current ramps up linearly. Then after 5us the mosfet is shut off ideally providing an open circuit and the inductor voltage ramps up to a high value. How can I calculate this high value of voltage?

To calculate the max current I used: VL = L * di/dt

Assume this is linear ramp so di/dt can be replaced by Delta I / Delta T where T is the time the switch is on for, and VL = 1 volt from source. So in my example this would be:

1 volt = 500uH * Imax / 5us => Imax = 10mA.

I ran this in LTSpice and it is indeed what I got, but I can't figure out how to calculate the voltage peak of the inductor which looks to be about 12 volts. I am trying to find this out for a high voltage source using a votlage ladder cause I need to minimize the switched voltage of the inductor to make sure it doesn't harm the IC.

Below is my spice model.

 

[anorlunda]

The part you're missing is the voltage across the mosfet during the current ramp. Just using Kirchoff's Law, the inductor voltage = supply voltage - mosfet voltage.

 

[DaveE]

This circuit is way more complicated than you think it is because of unavoidable parasitic elements that aren't shown in the basic schematic. If the switch (and everything else) was ideal, the inductor would generate an infinity short spike of infinitely high voltage to keep the current flowing until the ∫v dt across the inductor has caused the current to decrease to zero. In practice, there will be capacitance in the circuit which will cause the voltage to oscillate. Also, a real mosfet has a finite switching speed. Your simulator most likely includes these mosfet parameters, so the result will actually tell you more about the mosfet than the inductor.
To learn more you can google "inductor volt second balance", also "boost converter". This circuit is the primary side of a flyback converter, or a boost converter, both of which use this generated voltage. Usually the purpose is to increase the voltage from the source value.
In practice you will nearly always see an alternate path (usually through a diode) for the inductor current to flow. It's usually undesirable to try to make infinite voltage spikes. A good rule of thumb in circuit design: Don't try to change the current through an inductor instantly, and don't try to change the voltage on a capacitor instantly.