| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply limiter circuit capable of suppressing fluctuations in a secondary-side voltage with the fluctuation in load, when the light load is applied to a power supply apparatus equipped with a low-frequency power supply transformer. SOLUTION: An opening/closing element (FET) 11 turning on/off the connection between a bridge diode 5 and an electrolytic capacitor 6 and a power supply limiter circuit 1, including a control circuit 13 for controlling the opening/closing element 11 are provided between the secondary-side bridge diode 5 of the power supply apparatus 2 equipped with a low-frequency power supply transformer 4 and the electrolytic capacitor 6. The power supply limiter circuit 1 turns the FET 11 on/off, to control the load voltage to be constant at light-load time, when the load is light and the current necessary for driving the load 10 is small; whereas it supplies power to the load 10 by making good use of the characteristics of the low-frequency power supply transformer 4 which is lowered in the load voltage in proportion to the load current, without limiting the load voltage, at heavy-load time, when the load is heavy and sufficient current for driving the load 10 is required. Since the load voltage is constant at light-load, the cost of utilization components and installation space is suppressed. COPYRIGHT: (C)2006,JPO&NCIPI
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