Opening Statements by Panel Moderator:
Kevin Parmenter, PSD Contributor
It was my distinct pleasure to chair a podium session at PCIM in Nuremburg Germany in May. The subject of the session was enabling next generation power and the panelists were from the AMP, or Architects of Modern Power, organization. The three participants, in alphabetical order, were CUI, Ericsson and Murata.
In the spirit of full disclosure, Ericsson’s Power Modules group has been sold to Flex. Anticipating no change, the group’s official statement is as follows: “Ericsson Power Modules is fully committed to the activities of the The AMP Group as it continues to promote a consistent design experience by delivering power solutions optimized for specific applications with the assurance of unrivalled supply chain security through multi-source plug-and-play compatibility without the need for re-programming (from fellow AMP group members).”
The AMP Group collaborates on technology development and product roadmaps to create a complete power ecosystem. The stated goal of the organization is to “define the future of intelligent distributed power systems.” You can think of it being as the next-generation POLA and DOSA – moving forward by defining and driving standards on footprints, including pinouts, mechanical dimensions and electrical specifications and communications protocols.
The organization drives and defines standards in semiconductor controller ICs within the areas of power supplies and compatibility, with a key objective of providing source of supply through true multisource standards. In this they are innovative in that it they are creating a long-term agreement.
As a service to readers who could not attend the podium session at PCIM, the following articles offer summaries of the The AMP Group presentations.
Murata Power Solutions
Charlie Swiontek, Director of Strategic Marketing, Murata Power Solutions, co-founder of The AMP Group, along with CUI and Ericsson Power Modules
The evolution of digital power standards
Over recent years we have all seen digital processing progressing towards more massive integration and faster speeds. One of the ‘enablers’ for this was lower operating voltages for processors, gate arrays and ASICs giving the benefit of lower power consumption for a given clock speed. As speed and integration relentlessly increased further, power requirements caught up and became a performance bottleneck; currents into devices were now being measured in tens if not hundreds of amps. Improvements in power density and efficiency for the necessary AC-DC and DC-DC converters were just not keeping pace and a re-think was needed for the system power architecture to reduce heating and save energy all in a reducing footprint.
One of the solutions was to adopt a power ‘bus’ architecture with a large AC-DC converter followed by an isolated intermediate bus converter in turn providing typically 12 V to non-isolated switching voltage regulators adjacent to the power-hungry chips. This provided the most accurate voltage and shortest current paths with better overall efficiency. These ‘Point of Load’ converters (POLs) became common but each source was unique.
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Figure 1. The proliferation of supply rails at the board level has resulted in an intermediate bus architecture (IBA) that requires multiple POL converters on the system board.
Enter POLA (Point of Load Alliance) founded in 2003, a group of major power product manufacturers who worked together to define standard form-factors and footprints for non-isolated POLs. This was shortly followed in 2004 by DOSA (Distributed-Power Open Standards Alliance) agreeing standards for isolated ‘brick’ converters used to provide high power bus voltages to drive the POLs.
Good intentions were overtaken by technology however, when ‘digital’ power conversion became viable, then popular, and then necessary. The older POLs and bricks were ‘analogue’ designs with limited and similar functionality between competing designs whereas the digital conversion technology offered a wealth of programmable features. These ranged from dynamic adjustment of the converter control loop for best load transient response to remote adjustment of output voltage, current limit, start-up sequencing, fault threshold monitoring and much more. All this typically configurable over a serial interface.
If digital control of converters was to be implemented, it was now no longer possible to second-source a converter by size, pin-out and basic functionality alone; different manufacturers using different digital control and monitoring protocols defeated the compatibility dream. Although POLA and DOSA compatible products are still supported by manufacturers, the organizations have effectively become inactive in setting new standards.
Responding to the dilemma and with motivation to drive the progress of development of digital power, a new alliance was formed, the ‘Architects of Modern Power’ or The AMP Group. The first members, global power players CUI, Murata and Ericsson have committed significant resource and time to collaborate to offer true second sources for a common standard of digital power POLs and brick converters. The parts form elements of an evolving power ‘ecosystem’ with brick outputs matching the inputs of the POLs which can be paralleled for even more power. The development teams from the three companies work closely to ensure that customers can confidently swap between declared compatible products, knowing that the software configuration files are identical using the same digital controller, typically a 32-bit ARM processor. The same I2C serial interface is used across all devices to communicate with the converters using the PMbus™ protocol that has standardised instructions for read and write commands. A common GUI is also in development and Ericsson’s LGA (Land Grid Array) technology, developed for optimum reliability and performance, is an example of an intellectual property resource shared by the company with The AMP Group members for mutual benefit.
The very nature of digital control allows users to measure and monitor the performance of the converter so a user can compare and verify the equivalent performance of parts from the three manufacturers in a matter of a day or so.
The POL parts range in format from LGA types at the lower currents to SIP and DIP parts at high currents where through-pins are preferred. Currently topping the range is a SIP POL rated at a staggering 120A.
Isolated products include 264/300 W eighth bricks through 420/468 W quarter bricks to the newest offering due soon, a 1 kW isolated regulated bus converter in the through-hole eighth brick format. The brick converters all feature 2250 V rated isolation which is ideal for telecomms applications including PoE.
A common roadmap for future products is in place including AC-DCs in an agreed The AMP Group standard promising a complete, scalable ‘ecosystem’ of power.
The demands of data centers and servers drove the adoption of bus architectures, POLs and digital power because of their proliferation and urgent need for better power system efficiency. However, the same high-specification processing technology is being adopted increasingly in the industrial, medical and test and measurement areas.
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Figure 2. The AMP Group has already defined five distinct POL power converters, spanning 5A to 120A capability and three advanced-bus converters, spanning 265 W to 1 kW.
These markets have traditionally been more conservative, preferring time-proven designs of standard products that might have to be in service for decades. Support is paramount in these applications and users have rightly been suspicious of the ‘new kid on the block’ but digital control gives compelling benefits. Digital power can claim to have proven itself in critical data center/server applications but in fact, modern FPGAs practically need it anyway with their requirement for ‘adaptive voltage scaling’ - a technique that demands a dynamically adjustable supply voltage, varying with clock speed, workload and chip temperature to maximise performance and efficiency. The chips also typically require multiple power rails critically sequenced and timed on power up and down – a feature hard to achieve consistently across different analogue converter designs and certainly not field-programmable.
Interestingly, medical applications of imaging and data analytics now use the cloud as a necessity for computing power and collaboration and are a lesser known driver for data center expansion. It has been estimated that medical images amazingly make up as much as one third of globally stored data.
While digital power in the form of The AMP Group standards has enabled world class power conversion companies to collaborate and innovate while pooling market intelligence into technical trends, users have gained the benefits of better performance and true competitive second sources mitigating development risk and improving time to market. The world is a little greener as well.
Jeff Schnabel, Vice President of Global Marketing, co-founder of The AMP Group, along with Murata Power Solutions and Ericsson Power Modules
Pressure on Power in the Data Center
The data centers that sustain our digital lives are under pressure to deliver more services, to more users, more quickly. People are becoming increasingly comfortable with recording and sharing their lives online, particularly as more and more young millennials are getting connected and joining the conversation every day. The roll-out of 5G services promises to dramatically increase social sharing of images and video, but the relentlessly rising demand is not only driven by consumers. Emerging phenomena like the Internet of Things (IoT) and autonomous vehicles will connect untold numbers of extra data channels to the Cloud, to be stored, maintained, recombined, and processed in numerous ways by applications ranging from deep data analytics to machine learning.
Large data centers are known to be prodigious consumers of electricity. It is estimated that they already account for about 2% of global energy consumption, and this is set to increase. Operators are understandably keen, if not to reduce their total electricity consumption, then certainly to increase the proportion of the power they consume (and pay for) to do work that ultimately generates revenue. Moreover, the imperative to maximize IT workload density squeezes the power footprint, which calls for greater utilization of power capacity.
Digital power provides the means both to increase energy efficiency and to dynamically allocate power throughout the data center and so utilize the available real-estate efficiently. The ability simply to program a converter to behave optimally at various points in its load range helps overcome the trade-offs that must be accepted when working with conventional analog converters which behave according to fixed component values.
Going further, by exploiting the ability to connect individual converters as a network, gather data from each unit, and manage capacity in real-time as the data center’s needs change, unleashes more of the potential of digital power for boosting efficiency, utilization, uptime and productivity.
Partnering to Realize the Potential
Designing digital power modules, and software to manage them in real-time, is a more complex and multi-disciplinary challenge than creating conventional “analog” power supplies. And the pace of technical development in the applications that demand digital power is accelerating. Individual power companies can no longer “go it alone” if they are to stay a step ahead and deliver value and innovation for customers. The way forward lies in building partnerships to combine individual areas of expertise like digital power circuitry and power-management software.
Some of the most important challenges lie in optimally managing interconnected power modules, and demand advanced software to implement efficiency-boosting power-control strategies. CUI has worked with software specialist Virtual Power Systems to develop a complete digital power-management solution based on VPS’s Intelligent Control of Energy (ICE®) software platform. ICE enables data centers or other users of large digital-power networks to utilize power capacity efficiently and reduce ownership costs, taking advantage of techniques such as peak shaving, flexible power sharing and dynamic redundancy. This solution brings valuable new functionality, such as a console for managers to check status and analyze performance.
From a commercial point of view, large data centers or equipment makers are often reluctant to commit to a sole power-solutions provider, however advanced the technology or reputable the supplier. Having a feasible second source gives OEMs security against supply-chain problems. Today, given the complexity of digital power supplies and advanced software-based controls, a workable second-source proposition is about more than simply establishing common modules footprints and pin assignments, as was seen in standardization initiatives such as POLA and DOSA. The AMP Group initiative aims to establish a comprehensive set of board level standards for digital power, through deeper and more wide-ranging collaboration between partners, to give customers the assurances they need to take advantage of the benefits of this powerful new technology.
The AMP Group’s members are all leading power-module suppliers, each with a strong reputation for delivering high-performing, highly reliable power solutions using state-of-the-art technology. Working within the initiative, the group members remain independent and responsible for manufacturing and marketing their own product ranges. Where they come together is in establishing a common design approach that allows end-user communities to commit confidently to using advanced digital power and access the valuable benefits this new technology can deliver.
The potential is so great, and the prospects for progress so rapid, that a cross-company initiative like The AMP Group is the only way this can be achieved. If a single company were to take this on alone, aiming to set the pace of development and keep the technologies and profits to itself, customers would be unwilling to risk partnering with such an organization. Ultimately, digital-power technology and markets would fail to develop as quickly or reach their full potential, as compared to the approach CUI is taking together with Ericsson Power Modules and Murata. By working together, they expect to create a larger and healthier market for digital power technology than could be achieved by taking a conventional competitive approach.
Unlike earlier initiatives that focused on standardizing hardware, the AMP Group is working to develop common specifications that will allow true interoperability between digital power modules. This calls for a much deeper level of cooperation, for example standardizing responses to PMBus commands. The PMBus is a key enabler for digital power, but the specification can be ambiguous in the way some instructions are interpreted. The AMP Group has eliminated these ambiguities, so that all modules can be relied upon to respond in the same way to any given command.
Ecosystem Brings Accessibility
Users can now setup and manage digital and software-defined power supplies, and can safely assume these will behave as expected. The AMP Group is going further, to establish an ecosystem that greatly simplifies selection and configuration of modules from all group members, and helps exercise the full functionality of each module.
The aim of this is to consolidate support for compatible modules from each supplier under a single software platform to help designers configure the modules they need quickly and complete their designs without having to become experts in digital power.
The Group’s collaboration will continue to develop solutions to the challenges and opportunities that digital power will present as the technology continues to evolve. As CUI explores the opportunities for software-defined power, through The AMP Group and other collaborations, like working with VPS, it believes there is much more potential to discover. The roadmap is only just beginning to unfold.
Ericsson Power Modules
Martin Hägerdal, Head of Ericsson Power Modules, co-founder of The AMP Group, along with CUI and Murata Power Solutions
Power trends and the rise of digital power in the modern data center
In the data center of today, there are a number of ongoing trends in the industry that seek to maximize efficiency, reduce power consumption and minimize costs. The first major trend to recognize is that the complexity of power design is significantly increasing. Today’s motherboards will typically have 25 to 30 voltage rails or even more in some cases. In addition to which, the latest chipsets will typically be powered by multiple rails and all this requires complex tracking and power sequencing.
Another key trend is the growth in power demand: the supply current requirements for the latest microprocessors, SoCs and ASIC are forecast to rise to a level of 400 or 500 A in data centers and IP networks, and power demand per cabinet is increasing by a factor of four or five. However, while overall power demand is increasing, core voltages required by the latest microprocessors are becoming ever lower, down to 0.6 V or even less. This requires ever-stricter line regulation and tighter tolerances with increased transient performance.
Lastly, to meet the increasing use of AI and ‘big data’, along with the greater deployment of compute-intensive GPU accelerators working in conjunction with microprocessors, it is critical to make improvements in efficiency to meet the sharp rise in overall power demand.
The digital power concept was introduced and developed to meet these demands. In general, traditional analog switched-mode power converters will reach peak efficiency just below maximum load. Efficiency is also significantly lower at half load or at times of low demand. This is largely due to the use of fixed-value capacitors, which are employed to ensure stable supply over a wide range of operating conditions. The drawback is a lack of flexibility and the inability to deliver high or uniform efficiency across the potential range of loads. However, the possibilities offered by digital power can overcome this limitation.
A digital control loop can be easily and quickly changed and optimized via digital monitoring and control. In addition, the use of digital power converters requires fewer external components, thereby improving reliability and saving board space. In digital power based systems, communication is carried out via the PMBus, which defines the physical connection and the data exchange protocol between a central controller and power modules.
Adopters of digital power have seen the many advantages of its enhanced flexibility. The use of advanced simulation software can quickly determine the optimized number of capacitors used on each rail to ensure stability over a wide range of transients. Tools are also available to apply tracking and sequencing of power rails that have multiple loads for a given piece of silicon. In addition, output voltages can be changed on the fly, as well as the ability to monitor voltages, currents and temperatures.
An important next evolutionary step in digital power is the software-defined power architecture (SDPA). This introduces real-time adaptability to digital power supplies and has the potential to bring truly energy-efficient and power-optimized board-level capabilities into advanced network applications. Advanced processors are able to use software-controlled commands to adjust output voltages to increase processor performance or lower voltages at times of low load demand.
The SDPA is essentially a scheme that implements many advanced techniques including concepts such as dynamic bus voltage (DBV) and adaptive voltage scaling (AVS) as well as others, such as fragmented power distribution or phase spreading. DBV dynamically adjusts the intermediate bus voltage, which is widely used in the industry, as a function of load current to deliver higher power conversion efficiency. The second technique, AVS is used to optimize supply voltages and minimize energy consumption in modern high-performance microprocessors. It uses a real-time closed-loop approach to adjust the output voltage to optimize performance of individual processors.
Another key element in the development of power modules is packaging. The BGA (Ball Grid Array) has become extremely popular for devices such as microprocessors, memories and FPGAs that have a high I/O count, while also needing to occupy only a small space on a PCB. Ericsson is sharing its know-how in LGA (Land Grid Array) package technology with The AMP Group to enable a new generation of interoperable non-isolated POL converters that deliver industry-leading current density and thermal performance, and reliability.
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Figure 1. High-density I/O on LGAs allows many ground connections to reduce EMI
The LGA features large flat I/O pads instead of BGA solder balls: not only do these pads have outstanding low inductance, low EMI and efficient heat-flow characteristics, but also offer improved heat conduction through the pads into the motherboard. This benefits power converters as it allows more efficient cooling, particularly if the module design itself is optimized for this method of heat removal.
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Figure 2 – Ericsson’s BMR466 module offers high current density and is the first product to meet The AMP Group ‘gigaAMP’ standard, which defines a 60 A POL converter in a compact 25.1x14.1mm LGA
Developing Leading Technology
From the onset of digital power, Ericsson has been a leader in the field: in 2008, the company introduced both the industry’s first PMBus equipped advanced bus converter and POL converter. Since then, Ericsson has pursued continuous development with the launch of increasingly powerful modules, culminating with the launch in late 2016 of an AMP Group interoperable 120 A digital POL that is able to handle up to 480 A, when four units are operated in parallel. Ericsson plans to launch higher power quarter-brick modules before the end of 2017.
Ericsson continues to work with other co-founders of The AMP Group to develop power modules that offer a common mechanical footprint with electrical compatibility and the ability for power engineers to use the same configuration files for each AMP Group compatible device. The co-founders also continue to cooperate in the development of a GUI to enable fast power module configuration and verification of key electrical characteristics. The development of these common power conversion devices and technologies means the availability of multiple sources, benefiting power system architects across the industry.
Round-up by Kevin Parmenter
I believe these articles by AMP members exemplify the potential benefits of leaders working together towards a common goal. Moreover, it’s also significant that historically open standards in the technology industry provide great customer benefits and lower total cost-of-ownership, especially in applications where volumes can be high. The AMP Group consortium has the potential to go farther much faster than POLA and DOSA did. I encourage readers to review the information on the The AMP Group website.
The industry is anticipating explosive growth in wireless communications and the insatiable desire for more bandwidth and more data following the advent of 5G, the move toward connected transportation systems, and Silicon Valley’s disruption of the automotive market in general. Smart cities, IoT, and more, will create the need for efficient power in systems that will need high density, good value and high efficiency – all with a stable supply chain.
As technology moves forward to more complexity and integration, engineers are under pressure to design in multiple source components, which is often harder today than ever before. Having multiple sources should provide better price and delivery than alternative DC-DC converters can.
With market and technology leaders like AMP working together in this area and collaborating, it’s likely to attract other organizations and businesses to participate and bring what they have in semiconductor technology: packaging, materials, magnetics design, manufacturing expertise (which Flex has in spades). This is something to be seriously considered as the consortium moves forward the potential for a game-changing force, which could be highly disruptive to the industry and make a difference in new designs.