This invention provides a switching power supply control circuit based on the
parallel operation scheme that suppresses ripples in the output voltage. The control
circuit comprises switching circuit blocks 10 and 20 connected in
parallel, output reactors 31 and 32 connected in parallel corresponding
to the switching circuit blocks 10 and 20, and a control circuit
40 that controls the operation of the switching circuit blocks 10 and
20. The control circuit 40 comprises: means of calculating the difference
between the reactor currents IL1 and IL2 flowing through
the output reactors 31 and 32 and the average value of the reactor
currents, means of generating control voltages Vo1 and Vo2 corresponding
to the switching circuit blocks 10 and 20 based on the calculated
differences and the output voltage Vop comparators 48 and 49
that compare the control voltages Vo1 and Vo2 against
the reference voltage Vref and latch circuits 51 and 52 that
latch the outputs of the comparators 48 and 49 in response to the
clock signal CLK.
