June 06, 2019
| By: Christine Young
Blogger, Maxim Integrated
CPUs, field programmable gate arrays (FPGAs), digital signal processors (DSPs), and other processors are now handling heavy computational loads in portable electronic devices. Consumers increasingly expect their small, battery-powered electronic devices to provide long run-times between charges. This blog post highlights how dynamic power management capabilities in buck, or step-down, converters—key components of power supplies—can generate greater energy efficiency for entire systems that are powered by 1-, 2-, and 3-cell lithium-ion batteries.
Designers of compact portable devices must address challenges around high power consumption and heat dissipation. Because of this, power supplies for processors should have high voltage accuracy, high load transient performance, and high efficiency to support reliable processor performance.
In the not-too-distant past, handheld electronics required no or just one step-down converter to power their different functional blocks. A designer could use several low-dropout (LDO) linear regulators. Popular processors were typically at the 3V-3.3V range; an LDO works with reasonable efficiency using a single-cell lithium-ion battery input. As processing power demands continue rising, however, core voltages and typical I/O voltages have been dropping. LDOs are inefficient at low output voltages. In addition, they also tend to dissipate a lot of heat when operating from single- or multi-cell lithium-ion batteries.
Video game controllers provide an example of a portable, battery-powered device that can benefit from buck controllers in the power supply.
In this new portable design landscape, buck converters have emerged as an answer to the efficiency puzzle. When evaluating buck converters for small consumer electronic applications, here are some capabilities to consider:
The converter’s ability to be dynamically controlled to optimize its various parameters presents another useful feature. Consider, as an example, a system with a sensor requiring a 3.3V power rail and a Bluetooth component that requires only a 2.7V rail. The buck converter for the system will support the highest voltage requirement. However, this setup is inefficient for the lower voltage components, especially if the higher voltage component operates infrequently. Dynamic voltage scaling optimizes system efficiency by dynamically lowering the voltage of the buck converter to meet the requirements of the lower voltage components when the higher voltage component (the main sensor, in this example) is off.
Some multiphase buck converters on the market require larger inductors and more silicon area, while others don’t provide the current levels to support the latest CPUs and GPUs. Maxim offers a variety of highly efficient buck converters designed for application processors that require high current and low operating voltages:
Portable electronics continue to get smaller, while demanding more of their processors. These processors need highly efficient power supplies. This post explained how buck converters with features such as dynamic voltage scaling and low quiescent current can meet the needs. To learn more, read this white paper by Eric Pittana and Sami Nijim, “Generating Greater System Efficiency for Single- to Multi-Cell Battery-Powered Designs.”