Patent ID: 6876153

Claim:
A switching regulator circuit for controlling power supplied to a load, comprising: a switching device operable to repeatedly go on or off to control a voltage or a current applied to said load; a detector operable to detect a supply voltage or a supply current supplied to said load; and a controller operable to control a duration ratio of a period in which said switching device is on or off based on said supply voltage or said supply current detected by said detector, to control a value of said voltage applied to said load, wherein said controller includes: a saw-tooth wave generation unit operable to charge and discharge a saw-tooth wave generation capacitor grounded at one end to change a voltage at another end of said saw-tooth wave generation capacitor to a saw-tooth wave; a charge/discharge controller operable to change a ratio of a rate at which said saw-tooth wave generation capacitor is charged and a rate at which said saw-tooth wave generation capacitor is discharged, based on said supply voltage or said supply current detected by said detector; and a switching device controller operable to compare a voltage value of said saw-tooth wave generation capacitor with a predetermined threshold value and to control said duration ratio of said period in which said switching device is on or off based on the comparison result.