| 摘要 |
A step-up switching power supply circuit is provided. Within a delay period immediately after start of operation, a switching element (SW2) is subjected to constant-current control by a switching control signal (E) of a constant-current source buffer circuit (9). Control is also effected such that during halt of control for a stepping-up action in this circuit, or within the delay period, when an output voltage (VOUT)<an input voltage (VIN), a switching element (SW3) is brought into the ON state, and simultaneously, a switching element (SW4) is brought into the OFF state, or when VOUT>VIN, the switching element (SW3) is brought into the OFF state, and simultaneously, the switching element (SW4) is brought into the ON state, and after a lapse of the delay period, the switching element (SW3) is in the OFF state, and the switching element (SW4) is in the ON state, no matter which of the output voltage (VOUT) and the input voltage (VIN) is higher when compared by a comparator (12).
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