An inrush current prevention circuit for a DC-DC converter is provided and
in preferred aspects comprises a switching element that transforms an
input voltage by being switched on and off and outputs the transformed
voltage. A filter filtrates the outputted voltage, transformed via the
switching element, and outputs the filtrated voltage as an output
voltage. A reference voltage generator generates a reference voltage. An
error amplifier compares the reference voltage and output voltage and
outputs an error signal. A Pulse Width Modulation (PWM) signal generator
generates a PWM signal to switch on and off the switching element
according to the error signal. An on-off circuit either transmits or
isolates the PWM signal to the switching element. An Electronic Control
Unit (ECU) controls the on-off circuit. Preferred systems of the
invention can prevent an inrush current immediately following power input
or during reactivation of the DC-DC converter.