En route to painless portable USB charging

Users are fast taking to the USB port as the preferred way for portable device battery charging. But while the port eliminates a separate wall adapter, it has its power limitations: generally 2.5W maximum at no more than 500mA. More applications also call for charging portable devices away from the office or home, such as from the car. Here again, there's also a drawback to charging the device from the auto's cigarette lighter because of occasional line-voltage transients and surges that come from the alternator. These conditions require a well-protected battery charger IC.

The controller/manager topologies in some of the newer analog ICs offer a viable solution to many of these problems. Integrating both high-voltage capability and overvoltage protection features to handle automotive, Firewire and unregulated wall adapter inputs, they autonomously and seamlessly manage multiple input power sources to the system load and charge the battery while providing higher efficiency, faster charging times and instant-ON operation. These systems come in lower-profile packages and require few external components for handheld device applications such as personal navigators, media players, digital cameras, PDAs and smart phones. Here's what this class of chips, in this case Linear Technology's PowerPath manager ICs, do for you.

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