Abstract: A problem of the present invention is to provide a switching power supply device and a pulse width modulation circuit capable of operating stably in synchronization with a clock signal. To solve the problem, a pulse width modulation circuit 3A in a switching power supply device 1A includes square-wave voltage output means 8A for, when an integrated voltage Vn rises to an upper threshold voltage or more, shifting a square-wave voltage VPWM to L level, or when the voltage Vn drops to a lower threshold voltage or less, shifting the voltage VPWM to H level, and clock means 6A for outputting a first clock signal VCL1 and a second clock signal VCL2, which are 180° out of phase from each other.

Abstract: A problem of the present invention is to provide a switching power supply device and a pulse width modulation circuit capable of operating stably in synchronization with a clock signal. To solve the problem, a pulse width modulation circuit 3A in a switching power supply device 1A includes square-wave voltage output means 8A for, when an integrated voltage Vn rises to an upper threshold voltage or more, shifting a square-wave voltage VPWM to L level, or when the voltage Vn drops to a lower threshold voltage or less, shifting the voltage VPWM to H level, and clock means 6A for outputting a first clock signal VCL1 and a second clock signal VCL2, which are 180° out of phase from each other.

Abstract: A silicone rubber composition is prepared by mixing 100 parts by weight of an alkenyl-containing organopolysiloxane having a degree of polymerization of at least 3,000 and 5 to 30 parts by weight of finely divided silica having a specific surface of at least 50 m.sup.2 /g with 0.5 to 10 parts by weight of an organopolysiloxane resin having a weight average molecular weight of 500 to 50,000, a OH group content of 0.0001 to 0.01 mol/g, and a liquefying temperature of 50.degree. to 150.degree. C., at a temperature above the liquefying temperature of the resin. The composition has high plasticity in an uncured base compound form and is effective for extrusion molding. The composition cures into silicone rubber having low hardness, good flexibility and excellent physical properties, finding a variety of applications.