Tool/software: Code Composer Studio
I am confused on the derivation for the feedback sense resistors. In non-inverting mode it seems simple enough where the output is driven such that the FB node equals to V_ref and V_out = (V_ref / R_FBB) (R_FBT + R_FBB). From this you can calculate the resistor values for the given V_ref. However, in inverting model (since V_out is now negative) I am confused on what the FB node is being driven toward. If it were still trying to make FB equal to (positive) V_ref then the FB node would have to source current which doesn't really make sense and its no longer a simple resistor divider. However, looking at different datasheets on changing buck converters to inverting bb converters, the feedback equations seem to mostly stay the same, just V_out becomes negative http://www.ti.com/lit/an/slva317b/slva317b.pdf . Can anyone help clear up this confusion