As CMOS technology continues to scale to deep-submicron dimensions, highly integrated circuits, coupled with significant advances in battery capacity, have ushered in a new era of Consumer Electronics (CE) application devices and possibilities.
High levels of integration require advanced implementations of power and system management to handle the higher currents and decreasing system voltages in smaller packages. This in turn creates the need for thermal management. Further, battery power is increasingly critical as more systems move to portable formats. The ability to monitor system performance, drive up system efficiencies and maximize battery life, while providing rapid charging for various battery chemistries, are emerging areas of concern for providers of CE applications. To satisfy constraints placed by ever-shrinking form factors and functionality upgrades, advanced and highly integrated solutions for power supply generation, battery management, and dedicated system functions are becoming major factors in successful CE system design.
This analysis considers industry trends and challenges in power optimized mixed signal solutions providing system power management targeted at consumer applications, such as converged cellular, media player, and other portable media targeted for the CE marketplace.
Agere believes that power management is likely to be one of the fastest growing segments of the semiconductor market.
The power management and delivery systems in current CE applications are both sophisticated and complex. Traditionally, system functions are considered, designed, and integrated as disparate pieces; how they are powered and managed is generally considered an after-thought. In many cases, separate voltage regulators are used, which, depending on the number of functions that are added into the product, can involve as many as 10 or even 20 separate and distinct regulation elements. This type of “power management” and generation is costly, inefficient, and consumes expensive board real-estate; these are issues which run counter to CE-based application objectives.
For portable product designers and engineers, the digitally controlled, highly integrated, power and battery management IC (PMIC) will become a key component of system-level roadmaps geared at cutting-edge portable products. The development of digitally controlled PMICs is being driven by the promise of lower system costs, increased flexibility, and higher reliability.
Extending Battery Life
The key to extended battery life in feature laden portable applications is in designing efficient power generation circuits that offer intelligent power management. Such circuits are migrating from simple but inefficient voltage regulator circuits, to switch-mode regulator elements. This transition is especially important for low-voltage applications, which are the driving force for the CE market. The higher efficiencies attained through switched-mode regulators are welcomed by the mechanical design community as well, because along with the increased efficiencies comes lower heat dissipation. This, along with smaller external filtering components, allows the same features and functionalities to be packaged in increasingly confined areas. Switch-mode supplies, however, do have a drawback in that the pulse width modulation (PWM) used to generate power (which in turn, drives low-voltage components) tends to introduce more noise into sensitive circuits. Further, this topology tends to lose efficiency under light loads.
Another interesting development in the CE applications space is use of the “buck-boost” regulation element. This type of regulator is required in many battery-powered applications due to the system VBATT voltage characteristics of the lithium Ion (Li-Ion) battery supplies (see Figure 1), and because many of the IP blocks used in the applications are 3.3V core logic devices. A “buck-boost” regulator functions as a linear regulator when the VIN is greater then the VOUT (buck mode) but then transitions into a boost-mode regulator when the VIN falls below some given threshold.
In Li-Ion battery systems, the battery supplies sufficient voltage when fully charged to support the buck mode of operation. However, as battery capacity is consumed the battery output falls off, and at some point in time, the boost-mode of the buck-boost circuit must be engaged to step-up the battery voltage and appropriately supply voltage to the core logic of the load within the overall device specifications.
Figure 1 -- Battery Voltage Constraints