Meeting emerging power management needs

In the past, power conversion ICs for computing and communications applications were very simple to implement. Analog pulse width modulation (PWM) ICs had only two tasks: delivering power and regulating voltage . Other functions, such as monitoring or diagnostics, were not considered necessary. In the rare cases where these functions were needed, they were implemented with external chips .

Today, however, the need for efficient and reliable power management is growing at a rate much faster than Moore's Law. Major processing devices for computing and communications applications contain billions of transistors, and their power requirements are more precise and complex.

In data communications, boards with 36 to 40 voltage rails are emerging . In computing applications, motherboards often utilize more than 20 voltage rails to power various ASICs, memory, and processor chipsets. This complexity requires sophisticated diagnostics, control, and monitoring of many different parameters, which is beyond the capabilities of analog PWM. The typical solution is to add a separate microcontroller, but this greatly increases system cost and design complexity while taking up valuable space on increasingly smaller circuit boards.

System efficiency

Precision control inevitably leads to another issue: system efficiency. External factors such as increasing fuel costs and environmental pressures further highlight the importance of efficiency.

Computing applications consume less than 50% of their total power for data processing , with the majority of that power wasted in heat dissipation and system losses. The end result is that every watt of power wasted increases the application’s total cost of ownership and increases global energy consumption. Without the ability to measure and diagnose the system, it is nearly impossible to improve efficiency in real time. The typical analog power solution is a black box that provides no diagnostic information.

Faced with increasing price pressure, designers are increasingly looking for power supply solutions that integrate power supply diagnostics rather than standalone microprocessors. They want cost-effective solutions to monitor the chip's current , voltage, temperature, and power efficiency. System designers want their power supplies to provide fault reporting, I2C communication with PWM controllers, and flexible programming of personalized parameters for each voltage rail.

This all leads to a simple conclusion: Market dynamics and customer demands mean that Moore’s Law advancements in analog solutions are lagging behind current customer needs. The only way to meet today’s demands is to move to digital power solutions (see Figure 1).

Figure 1. Power management controller block diagram addresses the current need to move toward digital power solutions.

Some markets have already started the transition from analog to digital. For example, digital power is necessary to meet the complex power requirements of servers and high-end graphics cards. Other markets are also gradually making the transition. At first, the decision was simply based on cost. Analog PWM is mature, proven, and inexpensive. Switching to a digital solution would increase the total cost of the system. But now, the cost equation has changed. Considering system intelligence, fault handling, and other programmable features, analog solutions end up costing more than digital solutions. For markets like digital communications, analog solutions and the additional chips they require also do not meet their space requirements.

Digital Solutions

As with many new technologies, there is resistance to change. This resistance is natural and will diminish over time. Unfortunately, in addition to this natural resistance to change, there are two major misconceptions that plague digital power solutions.

The first misconception, surrounding cost, is resolved when developers weigh their options and realize that all the benefits of digital power management can now be realized at the same cost as analog solutions.

The second misconception is even more annoying and is the most severe barrier to widespread adoption of digital power solutions. This misconception is that digital solutions are so complex that customizing them for a specific application requires extensive training and a long design cycle. Is it worth the time spent designing? Some may think so, but fortunately, designers do not have to make that choice. The emergence of new digital power management solutions has made the complexity invisible to designers.

Just as PC users do not need to know the underlying code to use an application, power supply designers do not need to understand the programming to utilize a digital power solution. This promotes the adoption of this technology.

Early adopters are often technical experts who are eager to explore the benefits. However, for widespread adoption to occur, the complexity must be hidden through better and more intuitive user interfaces. The latest generation of digital power ICs brings hope to digital power solutions. It can communicate bidirectionally with processors, ASICs, and microprocessors responsible for coordinating power at the board and rack levels of power management (see Figure 2).

Figure 2. The latest generation of digital-power ICs can communicate bidirectionally with processors, ASICs, and microprocessors responsible for coordinating power.

After digitizing analog information, each piece of information can be multiplied, divided, added, transmitted, compensated, filtered, and stored. Since digital algorithms determine the technical specifications and performance of the entire chip , these digital power ICs can also implement nonlinear and asynchronous algorithms to improve transient performance.

All data is digital, so it is easy to transmit this information via the I2C bus. In addition, this technology can be easily adapted to future high-speed communication buses, achieving bus rates up to 33 MHz or 66 MHz. Thanks to these architectural features, digital power ICs that can meet complex system requirements will be very popular in the next decade.

Graphical User Interface

Digital power IC solutions also provide flexibility to system designers. Compensation, set points, OCP levels, OVP levels and all major parameters of the power design can be fully set using software. Through an intuitive graphical user interface (GUI), designers can optimize the output capacitors and inductors for a specific design without having to replace resistors or capacitors on the circuit board . Power solutions can be designed and implemented without replacing discrete components. The end result is not only increased system flexibility, but also a faster time to market for the end product.

Additionally, component aging and temperature drift calibration can be achieved once the product is deployed. In digital power ICs, each voltage rail can be designed and programmed individually. Digital power ICs can be easily implemented as multiple phases and run in parallel with synchronized timing of each phase, which reduces EMI interference signals for easy filtering. The rms input current is reduced , reducing the required input capacitance. Again, flexibility and custom design are achieved through software rather than hardware.

The key to achieving all of the above features is the intuitive graphical user interface (GUI). Now, even designers who are not familiar with digital power management can easily program output voltage, current, faults, PID coefficients for loop compensation and other key functions step by step by following the various selections displayed on the screen.

Designers can program each voltage rail on the motherboard and set the timing, tracking, rise time and programmable delay of each voltage rail individually. In this way, digital power ICs can not only implement PWM control, but also perform comprehensive power management on boards with multiple voltage rails and communicate with the system in real time.

Providing a graphical user interface (GUI) may seem trivial, but it is actually very important. Just as a better user interface has promoted the promotion of Linux systems, an intuitive graphical user interface (GUI) has also shortened the design time of digital power management solutions and eliminated the cost concerns of designers in this regard. Digital power ICs are not only advanced solutions provided by today's chip technology, but also the most cost-effective solutions.