| 摘要 |
PROBLEM TO BE SOLVED: To obtain a switching regulator which can set a load current accurately when PWM control and PFM control or VFM control are switched depending on the state of load without using a resistor for detecting the output current. SOLUTION: A current detection circuit 10 outputs a low level signal CMPout while the inductor current is zero, a capacitor C11 is charged through a PMOS transistor M11 with a constant current supplied from a constant current source 11 and turned up by a current mirror circuit consisting of PMOS transistors M13 and M14. While the signal CMPout is high level, the capacitor C11 is discharged by an NMOS transistor M12, and a PFM/PWM control circuit 2 switches the control mode from PWM control to PFM control when a low level switching signal Sc is input continuously more than once. COPYRIGHT: (C)2008,JPO&INPIT
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