| 摘要 |
<P>PROBLEM TO BE SOLVED: To ensure high speed response even when the load changes suddenly in a switching power supply device of fixed on time or fixed off time drive system. <P>SOLUTION: The switching power supply device which outputs a voltage having a potential different from that of an input voltage by performing the switching control of a current flowing through an inductor comprises a trigger signal generation circuit which generates and outputs a signal that imparts a timing of turning a switching element for driving on, a first timer which clocks the fixed on time of the switching element for driving, a second timer which clocks the off time of the switching element for driving, a sudden change of load detection circuit which detects sudden change of the load, and a drive pulse generation circuit which generates and outputs a drive pulse based on the outputs from the trigger signal generation circuit and the first and second timers. When the sudden change of load detection circuit detects sudden change of the load, a signal output from the first timer and indicating the end of on time is prohibited. <P>COPYRIGHT: (C)2012,JPO&INPIT |
