基于单片机的智能手机充电器的设计(英文版)(doc 11页)

基于单片机的智能手机充电器的设计内容提要：
In the era of global wireless connectivity, almost nothing is more important than keeping a smart phone or mobile Internet device charged. Expanding features on the constantly improving portable and handheld device create a major challenge for designers of battery charger ICs. High resolution screens and larger memories combine with new capabilities to tax the battery, requiring battery charger technology that is not only more efficient but also capable of managing power distribution.
Optimizing power consumption to prolong battery life has always been a driving force in handheld power management. However what is changing are the efficiency expectations for charging handheld devices when they are plugged into the wall. The latest generations of device designs are using high-efficiency switching chargers in place of traditional linear chargers. Customers today continue to demand shorter charge cycles when charging their battery. Beside higher efficiency with respect to the conventional linear chargers, one of the great advantages of using switching chargers solution is the capability to boost the charge current from what supplied by the source. This is especially important when powering off of a USB port where the current available might be limited to less than 500mA. Higher charge currents equate to shorter charge cycles    thus satisfying customer expectations.
There are two kinds of battery chargers used in most handhelds now – linear chargers and switching devices. Linear chargers have a longer history. They have typically provided a relatively efficient, simple way to charge portable devices, creating minimal noise without many external components. But as portable devices become more complex and add layers of new features, they need higher battery capacity. Linear chargers present liabilities due to power dissipation, which become clear if a user wants to charge a device while using at the same time. The heat generated while simultaneously using and charging can damage the system or battery. Not a good outcome.
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