Digital Power Is Mostly Analog

Focus:

This commentary offers a counterpoint to the numerous articles touting the advantages of digital power control over conventional analog control. Article discusses three different classes of functionality that are typically labelled as digital power before focusing on the digital switching regulator where the error amplifier and pulse width modulator are replaced by an A-D converter and digital signal processor. Even here, says the author, the regulator still requires many inherently analog functions such as the voltage reference, current-sense circuit, FET drivers, and power switches; plus the ADC is mostly analog, and the external capacitors and magnetic components are analog. The author goes on to argue that it does make sense to build parts in a complex semiconductor process with dense logic and high voltage elements, when the same functions can be produced more economically in a simple analog process.

What you’ll learn:

• How to understand the arguments for not designing or adopting switching regulators with true digital control

Notes:

At the time this article was published, Linear Technology offered no switching regulators with true digital control (it did offer traditional analog switching regulators with a digital interface.) However, just a few months later, Linear Technology began second sourcing Primarion's digital power controllers. See "Alliance Creates Dual Sources for Digital Power Controllers" at http://powerelectronics.com/power_management/primarion_linear_controllers/index.html .

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Author & Publication:

Steve Pietkiewicz, General Manager, Power Products, Linear Technology, Milpitas, Calif., Power Electronics Technology, Jan 01 2006

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