Hello there, I am trying to build a circuit that outputs ~180V with a LT1308A IC. The design is a modified version of the following circuit (pg 17 of the datasheet), using a 1:10 coupled inductor instead of a 1:12:

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It seems that eliminating the voltage doubler in the corner and changing the feedback resistors would achieve this rather simply, however it does not behave quite as expected when built in LTspice:

The output voltage (green) starts at -32V and ends at roughly 165V.
The switch pin (blue) sees about 108V, far exceeding its maximum rating of 36V.

What am I doing wrong here?

 

D1 should be a Zener diode. It performs a protective function when the stabilizer is not loaded. Its operating voltage must be less than the maximum allowed at the input SW. Your transformer has too large inductances. Take real values. For transformer L2 = 100 * L1.

 

D1 should be a Zener diode. It performs a protective function when the stabilizer is not loaded. Its operating voltage must be less than the maximum allowed at the input SW. Your transformer has too large inductances. Take real values. For transformer L2 = 100 * L1.

Replacing D1 with an appropriate Zener solved the switch pin voltage problem.
I believe L1 and L2 are correct values, according to their datasheet, unless my understanding is incorrect:

The bottom row is the unit being used.

 

This just in: My understanding was incorrect.
Should've been looking at the Primary inductance and determining the secondary using the turns ratio, not the DCR max values.

Things are looking much better, setting the inductance values to 2uH and 200uH, though my output range is now a stable -50v to 240v, vs. the 180v it should be.