Patent ID: 8335097
Filing Date: 2012-12-18
Classification: H02M,Y02B

Abstract:
1. A semiconductor device which controls a switching power supply that converts an input direct current voltage to a regulated output direct current voltage by intermittently switching on and off the input direct current voltage using a switching element, said semiconductor device comprising: an intermittent-oscillation control circuit which outputs an enable signal providing an instruction to execute the switching and an instruction to suspend the switching alternately; a turn-on control circuit which changes between an execution state and a suspension state of the switching according to the instructions of the enable signal, and outputs a turn-on signal which turns on the switching element with a switching period; and an intermittent-oscillation frequency control circuit which causes said turn-on control circuit to delay the changing between the execution state and the suspension state of the switching so that an intermittence period falls outside of a specific time range, the intermittence period including a period during which said turn-on control circuit is in the execution state and a period during which said turn-on control circuit is in the suspension state, wherein said intermittent-oscillation frequency control circuit includes: said intermittent-oscillation frequency control circuit delays the changing of said turn-on control circuit to the one of the execution state and the suspension state of the switching until an end of the second period in the case where the enable signal provides one of the instruction to execute the switching and the instruction to suspend the switching after an end of the first period and before the end of the second period.