Why has digital power conversion fallen out of favor?

　　The development of digital power supply

　　As electronic systems become more complex, with up to five voltage rails per processor and multiple processors per printed circuit board, power complexity has increased. Requirements such as tracking, sequencing and margin checking, as well as stringent regulation requirements down to 0.9V on voltage rails have led power experts to consider digital power as an effective alternative solution to these problems.

　　At present, new digital power controllers and power stage designs have many advanced features, such as redundant AC or DC power supplies, high efficiency of more than 90% within the working range, fault tolerance design, diagnosis and automatic measurement and recording of conduction. People often regard digital power solutions as the future power supply for some applications, such as wireless base stations, high-speed data voice, video networks, renewable energy applications, etc. For more expert advice and original reference designs, please pay attention to the [ Power Management Technology Forum ]
　　hosted by Electronics Fans Network on October 24, 2014 .

　　Digital Power Market Size and Growth Rate

　　The latest report from Darnell Group shows that the digital power IC market will reach nearly $800 million in sales in the next five years. The second edition of the report "Emerging Markets for Digital Power: Components, Converters, and System-Level Opportunities" surveys the global digital IC market, including VR loop control, non-VR loop controllers, power factor loop correction loop controllers, converter management ICs, and system ICs. Darnell predicts that the market sales will increase from $169 million in 2006 to $796 million in 2011, with a compound annual growth rate of 36.4%.

　　Darnell noted several factors that have influenced the growth of this market: Over the past few years, the market for digital power management and control products has grown significantly. More power converter companies are launching products that integrate digital power management and control IC solutions, including hybrid (analog and digital) and pure digital power supplies. At the same time, system manufacturers are trying to find the advantages of digital control and are actively launching their own solutions - usually some dedicated solutions.

　　Darnell's research shows that other economic factors will also become the inevitability of digital power replacing analog solutions. Analog IC technology follows its own Moore's Law, such as each generation of analog die size will shrink by 30% and the cost will drop by half every 4 to 8 years. For digital ICs, the die size will shrink by 2 times with each new generation of products or every 18 to 24 months.

　　However, since the cost of launching each new generation of products is 10% to 20% higher, it will take about 2 to 3 years to reduce the cost of digital power by 2 times. Manufacturing nodes that can produce digital power controllers at a lower cost than analog controllers have long been available. Darnell research shows that during the life of both semiconductor processes, it will become more cost-effective for use in commodity parts, such as power control ICs. The research company also noted that digital power is already cheaper than analog power if the specific application requires a "multi-function" solution.

　　Applications requiring digital power

　　Over the past few years, system designers have begun to view the power system/converter as the root of evil that must be considered in the overall success of future products.

　　Thirty years ago, the seeds for the industry’s transition from entrenched linear technology to switch-mode were sown. It was an uphill battle. But with the continued development of PWM controller ICs, as well as MOSFET enhancements and advances in packaging technology, switch-mode power supplies (SMPS) have been able to overcome the obstacles and dominate the market at all power levels. As switch-mode conversion has increased the impact on all front ends, form factors have continued to shrink, performance has continued to increase, and costs have continued to decrease. Linear products have a place because of their unique attributes.

　　Although digital power conversion has been popular for the past 10 years, its adoption has slowed down significantly due to the following three reasons.
　　First, the capacity of the analog engineer who designs the power stage, magnetic field and controller, in addition to the PCB layout. Now he needs to learn digital hardware and firmware knowledge or have a three-person working group around digital power design;
　　second, the cost-benefit ratio;
　　third, we should not forget that it took us more than 20 years to fully adopt switch-mode converters, and now the time is right. We must put all of the above reasons together with the application that only digital power can better solve the problem, and the analog solution cannot achieve this effect.

　　Although there have been many attempts to adopt digital power, digital power technology has not been widely adopted in any specific application that will bring about a turning point in the power industry. People are still considering whether there is a need for a high-volume PC market that drives the adoption of non-cost-sensitive 200A, multi-phase server core power supplies, or an N+1 redundant market that requires diagnostics and automatic measurement to record conduction. In any case, digital control must be able to meet all system-demanding performance requirements at the same price as analog solutions. Digital solutions must greatly expand the application field, providing breakthrough features that are difficult or never achieved in analog power systems.

　　Since the late 1990s, true digital power controllers have been evolving, i.e. true digital signal processors, micro-ASICs and state machines. Now, they are at a juncture where hardware, software and design tools are coming together to drive digital controllers to the same power envelope (turf) as analog. The availability of advanced design tools, demonstrated at this year’s Power Electronics Technology Conference and the Baltimore Show, has removed the daunting aspect of programming that plagues many experienced analog power designers. The advanced GUI features provided by these tools not only eliminate the need for programming, but also simplify power supply design, which are the two major obstacles besides cost. Development time is greatly reduced and efficiency is considerable. In addition, it opens the communication line between the host CPU and the power supply, allowing software to dynamically adjust the power supply configuration without changing the hardware. In addition, it also makes the power supply as a system-level functionality.

　　Digital controller vendors have invested enough money in the technology to list and demonstrate the inherent advantages of digital power to major end-equipment OEMs. Based on the adoption rate, some market analysts predict that this new technology will have a bright future. By the end of 2020, digital power converters will be on par with analog solutions.

　　One of the typical applications that requires a digital power controller is a solar inverter as shown below.

　　Solar inverter structure diagram

　　The solar inverter is a key component of the entire solar energy system. It is responsible for converting the variable DC output of the PV cells into a clean sine wave 50 or 60 Hz current suitable for supplying power to the commercial or local grid.

　　DSP Controller - Digital Signal Controller efficiently executes the high-precision algorithms required to charge the system battery and provide power to the grid without power loss. This is known as operating the system at its maximum power point. The driving of the DC/AC main bridge is implemented by the controller's highly flexible PWM peripherals.

　　Other applications are TETRA (Terrestrial Trunked Radio) base stations

　　The latest on digital power

　　The unpredictable effects of the converter's various error-prone components, such as the inductor, capacitors, and error amplifier, can be compensated by using a digital power controller that takes into account high-volume production tolerances.

　　There are many ways to bring these digital features together to create a power system that can meet the demanding power requirements of the most complex systems of today and tomorrow.

　　In fact, TI unveiled its latest solutions and product demonstrations for AC to DC-DC point-of-load applications at the 2009 Digital Power Forum, and also presented a number of technical papers on digital power.

　　The controller is configured using an easy-to-use Fusion Digital Power designer tool. This free and downloadable tool is designed to simplify the development process and speed time to market by allowing designers to easily configure many power supply parameters, including configuration of voltage and current thresholds with selectable default responses, supply voltage sequencing, monitoring, soft start/stop, tracking, margining, control loop response, phase management, and fan control. In addition, a reference design is provided for applications requiring ultra-high conversion efficiency, which uses integrated driver/MOSFET technology.