| 摘要 |
PROBLEM TO BE SOLVED: To obtain a switching regulator which can set the load current accurately when switching is made from VFM control to PWM control depending on the state of a load without using a resistor for detecting the output current, and to obtain a semiconductor device having that switching regulator. SOLUTION: Pulse width of a pulse signal CKO generated from a VFM pulse generation circuit 4 is set by the current value supplied from a constant current source 11 in the VFM pulse generation circuit 4, the capacitance of a capacitor C11 and a reference voltage Vs2, the pulse signal CKO is generated in response to a signal CMPout for detecting the fact that the excitation energy of an inductor L1 became zero, the amount of energy supplied by one switch cycle is determined by the pulse width of the pulse signal CKO which is determined by the VFM pulse generation circuit 4, and switching is made from VFM control to PWM control when the fact that the energy supplied by one switch cycle is deficient is detected. COPYRIGHT: (C)2008,JPO&INPIT
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