Power management system with charger and boost controller

Abstract

A power management system comprises a power conversion stage and a controller. The power conversion stage has two terminals. The first terminal is coupled to a first power source which provides a first voltage. The second terminal is selectively coupled to a second power source which provides a second voltage. The controller coupled to the power conversion stage can select a mode from at least a first mode and a second mode. In the first mode, the power conversion stage receives the first voltage at the first terminal and generates a step-up voltage at the second terminal. The generated step-up voltage is greater than the first voltage. In the second mode, the power conversion stage receives the second voltage at the second terminal and generates a step-down voltage at the first terminal for charging the first power source. The generated step-down voltage is less than the second voltage.

Description

[0001] Related Patent Applications [0002] This application claims priority to US Provisional Application No. 60 / 856,075, filed November 1, 2006, which is hereby incorporated by reference in its entirety. technical field [0003] The present invention relates to power management systems, and more particularly to power management systems with charger / boost controllers. Background technique [0004] Today, lithium-ion battery cell technology is gradually involving high power density battery cells. However, these high power density cells have the characteristic that the minimum discharged cell voltage is reduced (eg, to 2.2V). For example, since the battery voltage of a Li-ion battery with 2 cells (2-cell Li-ion battery) can range from 4.4V to 8.8V, a portable device powered by a 2-cell Li-ion The process of cell lithium-ion battery's 5V output voltage faces challenges. Therefore, in order to reliably generate a 5V output voltage, a new buck-boost converter is required to r...

AI Technical Summary

Problems solved by technology

Thus the buck / boost converter 200 requires multiple switches, which increases cost and reduces system efficiency

In addition, when the buck / boost converter 200 is operating in the buck mode, the switch 208 is often turned on, which causes excessive power loss

Similarly, when the buck / boost converter 200 works in the boost mode, the switch 202 is often turned on, which also causes excessive power loss

In addition, in the conversion stage, when the input voltage is almost equal to the output voltage, all the switches 202, 204, 206 and 208 will be in the active state, which also reduces the overall conversion efficiency

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