Patent ID: 8224399
Filing Date: 2012-07-17
Classification: H03F,H04B

Abstract:
1. An apparatus to supply a power voltage to a mobile device that has a switching power amplifier in a variable manner, the apparatus comprising: an external power supply to supply an external power using a battery or a cradle; an internal power supply to supply an internal power using power voltage supplied from the external power supply; a volume control unit to detect an installation of the external power supply and to generate a voltage control value corresponding to an audio volume value in accordance with the detection and a current audio volume value; and a DC-DC converter unit to convert a DC voltage of the internal power supply into a DC output voltage corresponding to the voltage control value generated in the volume control unit to control an output level of the switching power amplifier, the DC voltage being a boosted voltage that is increased until the switching power amplifier performs power switching at a predetermined pulse width modulation output level according to the boosted voltage supplied from the DC-DC converter unit instead of the voltage supplied from the internal power supply.