Traditionally, switching DC/DC converters (voltage regulators) were controlled using analog techniques because these were simple to implement and helped to maximize the power supply’s efficiency. Digital components were too slow and power greedy to challenge analog dominance.
However, over the past several years the introduction of high-speed, low power consumption and inexpensive silicon has rekindled interest in “digital power management.”
Armed with these new chips, designers are keen to take advantage of features such as the ease with which digital control enables optimization of the power supply by adaptation of a closed-loop response – even allowing adjustment “on the fly” to suit changes in the operating environment or to compensate for factors such as capacitive loading and component aging.
This article considers the benefits that digital power brings to voltage regulators by comparing an analog power supply with its digital equivalent. The article then continues by describing some of the latest digital regulators released by major vendors that take advantage of the control techniques discussed.
Control vs. efficiency
Efficiency is a critical design parameter of power supply engineering. In a simple switching step-down (“buck”) converter for a portable device, for example, the designer wants to lower the battery voltage to a level suitable for sensitive silicon but not waste any valuable millivolts in the process. Lossless conversion is impossible, but careful design can see modern switching buck regulators with better than 90 percent efficiency.