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Document Type and Number:
Japanese Patent JP2739706
Kind Code:

PURPOSE: To provide an AC-DC converter which has a wide applicable AC input voltage range by a method wherein the increase of the voltage in a circuit at the time of a light load is suppressed.
CONSTITUTION: A PWM circuit 6, a one-shot multivibrator 7, a pulse synthesizing circuit 8 and a comparing circuit 9 are provided in an AC-DC converter which is composed of a rectifier 3, a step-up chopper circuit 4 and a DC-DC converter circuit 5. The PWM circuit 6 generates a first pulse signal Vps and the one-shot multivibrator 7 generates a delay pulse VpD. In accordance with the first pulse signal Vpa and the delay pulse VpD, the pulse synthesizing circuit 8 generates a second pulse Vpa whose width is smaller than the width of the first pulse signal Vpa by the width of the delay pulse VpD. The comparator circuit 9 compares a voltage Vc which is stepped up by the step-up chopper circuit 4 with a reference voltage VREF and, if the voltage Vc is declined below the reference voltage VREF the generation of the delay pulse is stopped.

Ishii, Masanori
Arakawa, Koji
Application Number:
Publication Date:
April 15, 1998
Filing Date:
February 21, 1994
Export Citation:
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International Classes:
H02M7/217; H02M1/42; H02M3/155; H02M3/28; H02M3/335; H02M7/06; H02M7/12; (IPC1-7): H02M7/217; H02M3/155; H02M3/28
Domestic Patent References:
Attorney, Agent or Firm:
大田 優