A switching power converter current limit reference circuit generates an output-referred input current reference (or an input-referred output current reference) which takes into account a converter's input voltage, output voltage, and efficiency, thereby enabling implementation of a DC, or average, input current regulation scheme. A reference current (Iref) is provided which represents the desired average current limit. Circuitry multiplies Iref and the complement of the converter's duty cycle D (1-D) together. When Iref represents a desired input current limit, the resulting product represents the average output current achievable when Iref=Iin for the prevailing duty cycle D. When Iref represents a desired output current limit, the resulting product represents the average input current achievable when Iref=Iout for prevailing duty cycle D.