Batteries often serve as the main energy source for portable electronic devices. Although they depend on batteries, portable consumer electronic products, such as GPS devices and multi-media players, often consume energy directly from an ac-dc wall adapter or accessory power adapter (or “Auto Adapter”) when the battery is low or the device is in a stationary mode. Due to their cost effectiveness over their useful life, rechargeable batteries are often used for the power source of the portable elec tronic device. Attributes such as “relatively high energy density” and “mainte- nance free” make Lithium-Ion (Li-Ion) batteries popular in the portable consumer electronic products. Refer to the application note, AN1088, "Selecting the Right Bat- tery System For cost Sensitive Portable Applications While maintaining Excellent Quality" (DS01088) for characteristics of Li-Ion batteries. Some examples of how to properly design with Li-Ion batteries will be discussed in this application note. Depending on the product design or local government regulations, rechargeable batteries are often charged from inside the handheld devices or from battery charg- ing cradles. Due to the safety concerns or design concepts in certain regions, some batteries are required to be removed from the portable device prior charging activities are initiated. AN1149 Designing A Li-Ion Battery Charger and Load Sharing System With Microchip’s Stand-Alone Li-Ion Battery Charge Management Controller Author: Brian Chu However, most of the time, batteries are designed to be Microchip Technology Inc. recharged while the devices are still in the operational mode. An end user can extend the run time while refill- ing the energy back to the battery for the next mobile INTRODUCTION action. The power source now has to supply the devic……