Abstract: A DC-DC converter includes a switching transistor coupled to output terminals via an inductor and a rectifier. The converter also includes a circuit for sensing whether a current change in the main current path of the switching transistor reaches a given value subsequent to an initial current rise, if any, at the start of a conduction period. A control circuit is responsive to said sensing circuit to remove the drive to the switching transistor if said given value is reached.

Abstract: In a switched mode power supply of the push-pull type the drive to each output transistor is terminated just after its collector current reaches the value which the collector current of the other transistor had when the drive thereto was removed in the immediately preceding conduction period, in order to substantially equalize the drive to the output transformer contributed by each output transistor. This is done by means of sampling and storage circuits which store signals representative of the values of the collector currents in the two output transistors which occur when their drive is removed in combination with a comparison circuit which compares each stored value with the collector current of that transistor which conducts during the next conduction period.