Patent ID: 6359797
Filing Date: 2002-03-19
Classification: H02M

Abstract:
A DC/DC converter operating on the principle of a charge pump, comprisingat least one charge pump capacitor and a plurality of controllable switches connected thereto which are actuated during charge pump operation by a control circuit with an oscillator to generate across a storage capacitor applied to the output of the converter an output voltage deviating from the input voltage of the converter; and a comparator which compares a reference voltage to a voltage proportional to said output voltage of the converter and outputs a control signal for said control circuit, said control signal being at a first level when said output voltage drops below a predetermined design value and being at a second level when said output voltage exceeds said design value, said control circuit signalling said charge pump ON when said control signal changes from said second to said first level and signalling said charge pump OFF when said control signal changes from said first to said second level; a regulator circuit receiving said control signal of said comparator and converting it into a signal related to the momentary ON/OFF duration ratio of said charge pump with which it controls said ON resistance of one of said plurality of switches so that said ON/OFF duration ratio of said charge pump can be regulated to a predetermined design value, and a second controllable switch connected in parallel with said one switch whose ON resistance is controlled and which is controlled by said control circuit correspondingly thereto.