Patent ID: 7342326

Claim:
A circuit arrangement to which a motor vehicle electric system supply voltage from a high-voltage vehicle electric system is applied and for briefly maintaining at least one internal normal d.c. voltage for electronic circuits in the event of failure of the motor vehicle electric system supply voltage, comprising: a reserve energy accumulator to which a charging voltage higher than the at least one internal normal d.c. voltage is applied by the high-voltage vehicle electric system during regular operation, and wherein the reserve energy accumulator, in the event of failure of the motor vehicle electric system supply voltage, delivers a reserve voltage with which operation of at least one of the electronic circuits can be maintained for a period of time; and at least one step-down regulator that steps down an input direct voltage applied thereto to the at least one internal normal d.c. voltage, wherein the step-down regulator does not include an inductor, and wherein in regular operation the motor vehicle electric system supply voltage is applied directly by the high-voltage vehicle electric system via a diode as the charging voltage to the reserve energy accumulator and is also applied via a diode as an input direct voltage to the step-down regulator, and wherein the reserve voltage supplied by the reserve energy accumulator is applied directly as input direct voltage to the at least one step-down regulator in an emergency.