Trends in Digital Power Control and Integration
As the global marketplace becomes more competitive, innovation resulting in new applications for existing core technologies increasingly gains attention. In the power supply and semiconductor industries this emphasis focuses on trends in Digital Control and Integration.
Recently, several companies in these industries were asked to participate in a Question and Answer (Q & A) regarding these trends and what they have created through innovation: flexibility, lower-cost products, customization, optimization, and hybridization.
Electronic Products: Unlike Analog Control Digital Control has flexibility in its ability to adapt to changes in line and load conditions. What are some examples of Digital Control recently introduced, and what are the benefits of these examples from a functional and an investment perspective?
Patrick Le Fèvre, Marketing and Communication Director, Ericsson Power Modules: One of the best-known examples is the ability to modify parameters without hardware changes.
Benefits include the ability to adjust the Point-of-Load output via software, providing the ability to set precise voltages to load requirements, and the simplifying of complex architectures such as multiple POLs operated in parallel. Additionally, systems architects have a high degree of monitoring and control capability at the system and board level with granularity to a single POL, which allows for monitoring of system behavior, application of specific power profiles, and the collecting of data for use in preventive maintenance.
Mark Adams, Senior Vice President, CUI Inc.: Most controllers introduced recently have a type of auto-compensation scheme. Once the gold standard, it is now a minimum standard for consideration as a viable digital controller for high-value platforms.
Intersil recently introduced the ZL8800 family, which advances the scheme. Instead of a cycle-by-cycle concept, the controller provides an "always" compensated circuit with the ChargeMode Control.
The advantage of an auto-compensated controller is the ability to have an "always optimized" power supply. As a result designers can forgo the practice of building in margins for component aging, manufacturing variations, and temperature, which tend to mean higher concept cost and longer design cycles, and engineers do not have to rely on a fixed compensation in design - worst case scenario versus best case scenario.
David Norton, VP of Marketing,TDK-Lambda: Easy customization for numerous parameters – Overcurrent, peak loading, non-linear loads and parallel / redundant operation.
David New, Vice President of Product Marketing, Powervation: Our proprietary Auto-Control® technology is an example of how a digital architecture can bring true adaptive control into the DC/DC power conversion domain. The control is self-compensating, and occurs on a cycle-by-cycle basis, in real-time.
Auto-compensation technologies, in general, can provide ease-of-use benefits as well as time-to-market benefits to the design engineer, which include optimization of design:
• Adaptive auto-compensation provides reliability as the controller is able to continuously monitor and adapt to the system controlled, and optimizes its performance in response to the load. From the perspective of the Bode plot analysis, one can see that as the converter is used, and subjected to various loading conditions, the bandwidth and gain modulates according to the Proportional-Integral-Derivative (PID) coefficients that the controller selects as its optimizes for performance and stability. The improvement in gain and bandwidth result in an improved transient response.
• There are flexibility benefits, especially for adaptive auto-compensation. Power supply module vendors often design general-use modules that can be used in a variety of applications and to power different types of loads. As such, the designer often does not know the impedance of the board/system that their module will interface to or the exact input voltage level the module will receive. The engineer needs to factor these unknowns into the design, which can result in limitations in the range for which the product can be used. A power module utilizing adaptive auto-compensation can improve the flexibility and ease-of-use of the module as used in general applications, allowing it to be used over a wider range and with greater performance.
EP: Integration can be categorized as monolithic and hybrid. Monolithic integration is a pragmatic evolution of design and technology for power integrated circuits. Trends in design and technology that have resulted in this continuation have benefits and advantages. What are some examples and the related benefits and advantages?
Hybrid integration is the successful implementation of higher power ranges for power electronics. Thermal capabilities and reliability are some results of hybrid integration. The key to such success is the packaging, which involves innovative design utilizing new materials, new deposition technology, and design tools. What are some examples of hybrid integration in different markets, and what has been achieved through hybrid integration for producers of power electronics and customers?
Patrick Le Fèvre: Demanding applications such as high-performance and highly integrated servers leave little room for power sources, so an even higher level of integration is required. In low-power electronics, low-profile multi-chip modules make it possible to place these on the reverse side of the board, providing room on top for core components. In higher-power applications, hybrid integration combining powertrain elements with advanced cooling such as a composite heat pipe, will replace conventional power bricks. The benefit is an unprecedented level of available power that can operate with a limited airflow.
Mark Adams: The biggest advances have been the combination of drivers and MOSFETs, and the latest products have increased performance metrics. Additionally, density and board space reductions by using a driver/MOSFET combination can be considerable.
Recently hybrid integration experienced a significant crossover between semiconductor and power supply companies because customers want plug-and-play power and solutions that are small and simple.
Previously this was served by Point-Of-Load modules, but more companies are finding ways to provide a Power Supply in a Package. There are significant challenges with the PSiP concept, and performance benchmarks can differ between the solutions.
When a POL manufacturer designs a module, they have the ability to select and combine the best materials. The module company then looks at the tradeoff between cost and performance, and creates the best mix of technologies to meet market requirements.
A PSiP designer has a limited set of options available to create a solution. Every customer application is unique and sometimes the nature of the PSiP is the right solution, while other times the performance capability of the POL is appropriate.
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