Apparatus for converting DC to DC having non-feed back variable hysteretic current-mode control for maintaining approximately constant frequency

摘要

An hysteretic current-mode controlled DC to DC converter has an input voltage, an output voltage and a control switch. The switch alternately coupled the input voltage into an energy storage inductor. It is controlled by an hysteretic conparater sensing the current of the inductor and having turn-on and turn-off limits. The limits are symmetrical about an average inductor current. The limits are adjusted by simple non-closed-loop methods to maintain an approximately constant frequency of oscillation. The average inductor current is controlled by an error amplifier to maintain a constant output voltage. The two controls are independent.