| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching regulator which can set the load current accurately when PWM control and PFM control or VFM control are switched depending on the state of a load without using a resistor for detecting output current, and to provide a control circuit and an operation control method of the switching regulator. SOLUTION: An idle period is detected by comparing the phases of a control signal PHSIDE and the output signal CMPout from a comparator 3 and then masked for a predetermined time by an integration circuit consisting of a resistor R1 and a capacitor C2. The time of idle period for switching from PWM control to PFM control is set by the time constant of the integration circuit. Time constant of the integration circuit is set such that a pulse of low level is generated in a switching signal Sc at a moment in time when the time of idle period corresponding to a desired load current becoming a decision criterion at the time of switching from PWM control to PFM control has elapsed. COPYRIGHT: (C)2008,JPO&INPIT
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