Patent ID: 6977826

Claim:
A voltage regulator for use in a charging device of a portable electronic apparatus, comprising: a transformer having a primary winding and a secondary winding; a switch circuit being controlled via a control end thereof so as to result in a variable current on said primary winding; a rectification circuit electrically connected to said secondary winding, and proceeding a charging operation in response to an induced current, wherein said rectification circuit includes a rectifying diode and a capacitor electrically connected to each other in series and further electrically connected to said secondary winding; and a micro-controller electrically connected to said switch circuit and generating a first pulse width modulation (PWM) signal with a first duty cycle to said transformer until said capacitor has a voltage reaching a maximum voltage when said capacitor has a voltage smaller than a threshold voltage such that said transformer generates a charging current in response to said first pulse width modulation signal, and said micro-controller generating a second PWM signal with a second duty cycle to said transformer until said capacitor has a voltage reaching said maximum voltage by said charging current when said capacitor has a voltage between said threshold voltage and said maximum voltage such that said transformer generates said charging current in response to said second PWM signal, wherein said first duty cycle is greater than said second duty cycle to permit simultaneously using at least two high power-consumption devices in the portable electronic apparatus.