Multiple output switching power supply

Claim 1

A multiple output switching power comprising: a series connection of a D.C. input power supply, a switching device and a primary winding of a first transformer for supplying currents to loads during an on period of said switching device, so that m constant output voltages V i ( i =1, 2, . . ., m,m ≧2) are supplied to said loads from m secondary windings w i of said first transformer by on-off switching of said switching device; and means connected in series with the primary winding of said first transformer for storing a magnetic energy during the on period of said switching device and discharging the stored energy to the loads during an off period, wherein in order to produce a predetemined output voltage V j , the number of turns n j (j=2, 3, . . ., m) of a j-th secondary winding w j is determined by a first formula, V.sub.j =(N.sub.J /N.sub.1)·(V.sub.1 +k.sub.1)-k.sub.j where V 1 is an output voltage of a first secondary winding w 1 , n 1 is the number of turns of said first secondary winding w 1 , n j /n 1 is a turns ratio of said j-th secondary winding w j to said first secondary winding w 1 , k 1 is a voltage drop in a circuit of said first secondary winding w 1 , and k j is a voltage drop in a circuit of said j-th secondary winding w j .