| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply which quickens load transient responsiveness with an ON time fixed control method, reduces an output ripple voltage and further can operate even in the case where an input/output voltage difference is large.SOLUTION: On the basis of the ripple of an output voltage VOUT detected by a ripple voltage detection circuit 104 and a current change of a second power MOS transistor 2 detected by an inverse current detection circuit 105, an OFF time of a first power MOS transistor 1 is controlled by using a minimum OFF time setting circuit 55. Therefore, even in the case where the output voltage ripple is small, a circuit operation can be controlled and an output capacitor 21 of low equivalent serial resistance is available. Further, in the case of a load transient response, a duty and a frequency can be simultaneously maximized by the minimum OFF time setting circuit 55, such that the circuit operation can be quickly stabilized in a normal state. |
