| 摘要 |
PROBLEM TO BE SOLVED: To effectively remove ripple voltage which is being superposed on feedback voltage, proportional to the output voltage, and also to quickly start its boosting action, when the voltage of input power is lowered. SOLUTION: When the voltage (Vba) of input power is normal, this circuit outputs voltage equal to its value as output voltage (Vpp). When the output voltage drops, it PWM-modulates the feedback voltage (V1), which is obtained by dividing the potential of its output voltage, after passing through a low-pass filter (5a), so as to generate a pulse voltage (V4) where the pulse width increases as the feedback voltage drops. It operates a DC/DC converter (2) which receives the voltage of input power so that the boosting capacity becomes stronger, the larger the pulse width becomes. The low-pass filter is composed of a resistor network (8) and a capacitor (C2), and it switches the resistance value of the resistor network to be smaller in a period, when the pulse width is not outputted, and to be larger in a period, when it is outputted. COPYRIGHT: (C)2005,JPO&NCIPI
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