| 摘要 |
PROBLEM TO BE SOLVED: To release a latch state of a switching power supply unit in a short time in such a state that the switching power supply unit is in a shutdown latch state. SOLUTION: An error memory capacitor is not connected to a discharge resistor in such a state that a main power supply switch is turned on. When the shutdown is performed by power failure so that the switching power supply is in the latch state and the main power supply switch is turned off by a user, a discharging circuit switch is turned on so that the error memory capacitor may be connected to the discharge resistor. Thus, an electric charge in the error memory capacitor is instantaneously discharged through the discharge resistor, so that an ERR terminal voltage is instantaneously a specified value or lower necessary for releasing the latch to release the latch state in the short time. The main power switch is turned on again to normally operate the switching power supply. Consequently, the latch state can be released immediately after the main power supply is turned off, thus attaining high usability. COPYRIGHT: (C)2006,JPO&NCIPI
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