Battery Charging Options for Portable Products

Few components in portable system design have as pervasive an impact on the user's experience with the product as the power source and the system used to charge it. The length of time the battery holds a charge, the number of charge cycles the battery can endure, and the amount of time it takes to recharge the battery are key factors in the user's perception of the product's quality. Each of these factors is driven by the battery charging system and, by analyzing the key tradeoffs inherent in leading battery charging technologies, will attempt to help designers identify the optimal solution for their application. The specification of a power source and its charging system begins with the definition of the system's battery capacity requirements. A number of factors play into that determination. First and foremost is the basic system power consumption based on its design, including the number and type of subsystems, the number and type of displays, and the power efficiency of the core processor and memory. Those basic requirements must then be weighed against a variety of tradeoffs, such as the system's physical space constraints, the target operating time between charges, and the ability of software developers to build in power management features to extend battery life.