I am unable to get the LTC3805 to start at any voltage less that 8.6V. I've played with a number of variation of the downloadable demo circuit on the tools and simulations page at https://www.analog.com/en/products/ltc3805.html#product-tools, and the schematic for the 12V output demo circuit 1576A at https://www.analog.com/media/en/dsp-documentation/evaluation-kit-manuals/dc1576A.pdf.
Is it possible there is a problem with the model? (Don't see a version number in LTSpice Help->About, but date is Jan 22, 2020).
In the screen shot below I've replaced the Vcc input resistor with a "low impedance source" per the data sheet, likewise dropped the RUN input resistor, and disconnected the soft-start cap. Multiple variations on connecting/disconnecting, and modifying values have not produced startup at less than the 8.6V shown. As mentioned I've also implemented a version emulating values in the 1576A demo circuit schematic without startup at less than 8.6V.
Any other thoughts welcome.
Dazed and confused, tom@ballister.com
