According to the constraints specified in the data sheet for the LT8330, the SEPIC inverting converter voltage output can be no greater than half that of the non-inverting boost converter. At least, this is what I read considering the limits that can be used in the FBX voltage divider resistors.I need to generate -48V (from +12 in) and it need not supply much current - it's used in an electrostatic application. I've already configured a design for its opposite, a +48V boost, which fits into the FBX range without any worries. Oddly, the LT Spice model, using the standard values on the data sheet for a -24V converter, achieves only -14.5V.Can the LT8330 be extended to -48V out by exceeding the FBX limits and achieve a reasonably stable voltage? (+-0.1v is fine here, plus noise). Or, are there better solutions?
Thanks for the post.
The negative counterpart of the SEPIC is commonly called a Cuk.
The voltage across the coupling capacitor on a Cuk is VIN + VOUT, but the equivalent capacitor voltage on a SEPIC is…
I briefly considered a doubler, and especially given the circuit charges an element and draws virtually no current. In the end, I moved to the LT8570 which, fortunately, has a very nice and apparently tested design for -48V.
Thanks for the suggestions!