| 摘要 |
A current-mode switching power supply is provided, in which there is no unstable operation arising from the fact that signals to generate PWM signals are minute, even when a load is light and a switching frequency is high. In a switching power supply of this invention, an added slope signal is superposed in an early stage of a rise of a current detection signal, so that a combined signal Vsig is caused to reach a certain magnitude even when the load is light and the switching frequency is high, and consequently an output FB of an error amplifier ERRAMP which is balanced with the combined signal is also increased. By this means, even in a current mode, it is possible to eliminate unstable operation arising from the fact that the feedback signal FB which is the output of the error amplifier ERRAMP and the combined signal Vsig are minute.
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