| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a DC voltage step-up/down circuit which directly reflects fluctuation in an input voltage in determining a duty ratio and obtains a stable output voltage without complicating the circuitry. <P>SOLUTION: In the DC voltage step-up/down circuits 1a, 1a' (1b, 1b'), an unambiguously and continuously determined duty ratio Dy1 (Dy2) is computed based on an input voltage Vs and target output voltage Vo<SP>*</SP>, the duty ratio Dy1 (Dy2) is defined as a command signal of a switch S2 (switch S1), and a shift duty ratio Ds1 (Ds2) obtained by adding (subtracting) a voltage step-up/down control duty ratio δ1 (δ2) of the input voltage Vs to/(from) the duty ratio Dy1 (Dy2) is defined as a command signal of the switch S1 (switch S2). When the duty ratio Dy1 (shift duty ratio Ds2) is below zero, the switch S2 is fixed to off, while when the shift dury ratio Ds1 (duty ratio Dy2) is one or above, the switch S1 is fixed to on. <P>COPYRIGHT: (C)2010,JPO&INPIT |
