1. Field of the Invention
The present invention relates to an electronic device and a control method thereof, and more particularly, to an electronic device and a control method thereof, in which power required to drive the electronic device is relatively low, for example, in the case of a portable electronic device using a battery, a running time and a life span of a battery are increased.
2. Description of the Related Art
Generally, an electronic device employing a battery, for example, a portable computer such as a laptop computer, a notebook computer, a personal digital assistant (PDA) or the like, a mobile phone, a compact disc (CD) player, a video camcorder, etc., has been widely used because it is portable and capable of being used while a user moves. Further, such portable electronic devices are generally capable of employing a commercial alternating current (AC) power source via an adapter as well as the battery as the power source for the device.
As the various portable electronic devices are developed, technology related to the battery used in the portable electronic devices is becoming more important. The reason why the technology related to the battery is important is because the power supply is indispensable in the case where a user uses the portable electronic device while moving. Accordingly, various technologies have been developed to increase the capacity and running time of the battery. Further, there has been actively researched a method of increasing running time of the portable electronic device under the same battery power, that is, a method of minimizing power consumption of the portable electronic device.
FIG. 1 is a control block diagram illustrating a power supplying system in a conventional electronic device. As shown therein, a conventional electronic device comprises a main system 130 provided with a plurality of electronic components to perform a main function of the electronic device; a power supply 110 including an adapter 111 and/or a battery 112 to supply power to the electronic device; and a microcomputer 120 controlling the power supplied from the power supply 110. Further, the conventional electronic device comprises a linear voltage regulator (LVR) 150 to regulate the power supplied from the power supply 110 into power for driving the microcomputer 120; and a plurality of switching voltage regulators (SVR) 160a, 160b, 160c and 160n to regulate the power supplied from the power supply 110 into power to drive the plurality of electronic components of the main system 130, respectively.
The microcomputer 120 receives the power from the linear voltage regulator 150 and is generally maintained in a turned on state even when the electronic device is turned off. Here the microcomputer 120 senses whether a power signal is output from a power signal generator 170 when a user pushes a power button (not shown) and controls the power supplied from the respective switching voltage regulators 160a, 160b, 160c and 160n to the main system 130, thereby turning on or off the electronic device.
A power switch 113 controls supply of power from one of the adapter 111 and the battery 112 to the linear voltage regulator 150 and the switching voltage regulators 160a, 160b, 160c and 160n. 
The linear voltage regulator 150 is generally employed to supply the power to the microcomputer 120 because it has advantages of stable constant voltage output, low ripple voltage, and low noise. Further, each switching voltage regulator 160a, 160b, 160c and 160n is generally employed to supply the power to the respective electric components of the main system 130 requiring various voltage levels. For example, in a mobile phone, the display may be supplied with a different voltage level than the microprocessor. The SVR arrangement has advantages such as that the power-transformation efficiency is relatively high, and the size and the weight thereof are small and light, respectively. For example, a transformer in a switching voltage regulator can have a small size because the switching voltage regulator 160a, 160b, 160c and 160n operates at high frequency, and heat generation is relatively low.
However, in the conventional power supplying system, where the linear voltage regulator 150 is employed to supply the power required to drive the microcomputer 120, there arises a problem that the low power-transformation efficiency of the linear voltage regulator 150 inherently incurs a heavy power loss. Specifically, the linear voltage regulator 150 has a power transformation efficiency of about 17%, so that the linear voltage regulator 150 results in a loss of 80% or more of the input power.
Particularly, in a portable electronic device, the forgoing unwanted power loss of the power supply system is closely interrelated with the running time of the battery 112 for the portable electronic device, so that technology for reducing the power loss is badly needed even if the power loss is slight.
Instead of the linear voltage regulator, if the switching voltage regulator that has an inherent power-transformation efficiency higher than that of the linear voltage regulator is employed to supply the power to the microcomputer, an additional control circuit (not shown) to control the switching voltage regulator is required. However, total power consumption due to the control circuit and the switching voltage regulator is greater than that due to the linear voltage regulator, so that the switching voltage regulator is inadequate for supplying the power to the microcomputer.