Design A Load Sharing System Power Path Management with Microchip's Stand-Alone Li-Ion Battery Charger

AN1149 Designing A Li-Ion Battery Charger and Load Sharing System With Microchip's Stand-Alone Li-Ion Battery Charge Management Controller However, most of the time, batteries are designed to be Author: Brian Chu recharged while the devices are still in the operational Microchip Technology Inc. mode. An end user can extend the run time while refill- ing the energy back to the battery for the next mobile action. The power source now has to supply the device INTRODUCTION while charging the battery. The battery can deliver Batteries often serve as the main energy source for energy to the system load when the power source is portable electronic devices. Although they depend on absent as depicted in Figure 1. batteries, portable consumer electronic products, such Portable electronic devices have dramatically changed as GPS devices and multi-media players, often the way people live and work. They play an important consume energy directly from an ac-dc wall adapter or role in a person's daily life from every day tasks to accessory power adapter (or "Auto Adapter") when the entertainment. With the emerging technologies that are battery is low or the device is in a stationary mode. available today, portable electronic designers are trying Due to their cost effectiveness over their useful life, to integrate more features into smaller and lighter form rechargeable batteries are often used for the power factors while extending the system run times. source of the portable electronic device. Attributes This application note shows how to take advantage of such as "relatively high energy density" and "mainte- Microchip's fully integrated simple Li-Ion battery charge nance free" make Lithium-Ion (Li-Ion) batteries popular management controllers with common directional in the portable consumer electronic products. Refer to control to build a system and battery load sharing the application note, AN1088, "Selecting the Right Bat- circuitry. The solutions are ideal for use in cost-sensi- tery System For cost Sensitive Portable Applications tive applications that can also accelerate the product While maintaining Excellent Quality" (DS01088) for time-to-market rate. 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. System Load *Battery Charger Power *Protection Circuits Battery supplies system load Supply *Voltage Regulator