| 摘要 |
PURPOSE:To obtain a constant voltage DC power source circuit which can automatically correspond without setting a switch or the like by generating an output pulse which varies in the repetition period in response to the DC input voltage and corresponding to the DC input voltage of a wide range. CONSTITUTION:An input voltage detector 14 detects a supplied voltage Vc to transistors Q1a, Q1b, and applied it to a VCO 12a, which generates a rectangular pulse which has an oscillating period proportional to the supplied voltage Vc. In other words, when Vin is 100V, it applies a rectangular wave pulse of period (tau) and when Vin is 200V, it applies a rectangular wave pulse of period 2tau, to a pulse width controller 11, thereby corresponding to the drive repetition periods of the transistors Q1a, Q1b. The output signal compared of the outpt voltage Vout with the reference voltage Vref is applied to the controller 11, thereby controlling the pulse width. In this manner, the variation in the input voltage is proved by the period control of the former VCO 12a, and the variation in the load current is proved by the latter pulse width control. |
