Navigating the World of Power Conversion: From SMPS to Space-Level DC-DC Converters

Introduction:

In the landscape of electronics, the efficient conversion of power is paramount. Whether it’s for everyday consumer gadgets or critical military and aerospace applications, the ability to convert direct current (DC) from one voltage level to another is a fundamental requirement.  Power conversion plays a critical role in ensuring efficiency, reliability, and safety. From everyday consumer gadgets to complex military and aerospace applications, the demand for power conversion solutions tailored to specific requirements is ever-present. In this article, we delve into the intricacies of Switched-Mode Power Supplies (SMPS), linear regulators, military DC-DC converters, and space-level hybrid DC-DC converters, exploring their functions, applications, and the stringent standards they must meet.

Understanding DC-DC Converters:

At its core, a DC-DC converter is an electronic circuit or electromechanical device designed to convert DC power from one voltage level to another. They are essential components in systems where the power source and load requirements differ. This conversion is vital across a wide range of applications, from low-power devices like batteries to high-voltage power transmission systems. DC-DC converters come in various types and forms, each tailored to specific power level and efficiency requirements. These converters come in various configurations, including buck, boost, buck-boost, and isolated types, each catering to specific application needs.

Applications Across Industries:

DC-DC converters find application in a multitude of industries, ranging from portable electronic devices to spacecraft power systems. In consumer electronics, they power devices like cellphones and laptops, efficiently managing power from batteries. Additionally, these converters are integral to military equipment, providing reliable power in harsh environments and demanding conditions. They are also indispensable in aerospace applications, where radiation tolerance and reliability are paramount.

Types of DC-DC Converters:

DC-DC converters come in two main types: isolated and non-isolated. Isolated converters provide electrical isolation between input and output, crucial for safety and noise reduction in sensitive applications. Common examples include forward converters, flyback converters, and full-bridge converters. Non-isolated converters, on the other hand, do not provide electrical isolation and are commonly used in applications where isolation is not required. Examples include boost converters, buck converters, and buck-boost converters.

Advanced Conversion Techniques

Switched-Mode Power Supplies (SMPS) and linear regulators are two fundamental approaches to power conversion. The integration of multiple sub-circuits within electronic devices often leads to varying voltage requirements, necessitating efficient power management solutions.

Modern DC-DC converters utilize switching techniques to achieve efficient power conversion. These converters store input energy temporarily and release it at a different voltage, utilizing components like inductors and capacitors. Switching conversion is highly efficient, typically ranging from 75% to 98%, compared to linear voltage regulation, which dissipates excess power as heat. Recent advancements in semiconductor technology have further improved efficiency and reduced component size, driving innovation in the field.

Switched DC to DC converters have emerged as a vital component in addressing these diverse voltage needs, particularly in scenarios where battery voltage decreases with usage. These converters come in two main types: isolated and non-isolated, each offering distinct advantages in voltage translation. Leveraging switching techniques, these converters store input energy temporarily and release it at a different voltage, significantly improving power efficiency compared to linear regulation methods.

Advancements in semiconductor technology, particularly the utilization of power FETs, have enhanced the efficiency and performance of DC-DC converters, reducing switching losses and improving battery endurance in portable devices. Synchronous rectification using power FETs has replaced traditional flywheel diodes, further enhancing efficiency. While most converters function unidirectionally, bidirectional capabilities have become feasible through active rectification, catering to applications like regenerative braking in vehicles.

Despite their efficiency and compactness, switching converters pose challenges due to their electronic complexity and potential electromagnetic interference. However, ongoing advancements in chip design and circuit layout aim to mitigate these issues. Additionally, linear regulators continue to serve specific applications requiring stable output voltages, albeit with higher power dissipation. Other alternative circuits, such as capacitive voltage doublers and magnetic DC-to-DC converters, offer specialized solutions for certain scenarios, showcasing the versatility of power management technologies.

SMPS, characterized by their high efficiency and compact size, regulate output voltage by rapidly switching a series semiconductor device on and off. On the other hand, linear regulators, while simpler in design, dissipate excess power as heat, making them less efficient but suitable for applications where low noise and simplicity are paramount.

Military DC-DC Converters:

In military applications, where reliability and ruggedness are non-negotiable, DC-DC converters designed for military use undergo rigorous testing and qualification processes. These converters must meet stringent standards for environmental performance, including shock, vibration, temperature extremes, and electromagnetic interference (EMI).

Furthermore, in defense & aerospace industry, design of DC-DC converter has undergone transformation due to several silent technology drivers over the last decade. New military and aerospace programs, airborne drones, homeland security, and future warrior technologies are all striving for lightweight, low-cost, and highly reliable electronic packages that are offered by DC-DC converters. DC-DC converters are also used in military vehicles for various applications such as autonomous vehicle computing, mobile security equipment, and vision systems among others. Considering all these factors, the demand for DC-DC converter market is expected to rise in coming years.

Military-grade converters adhere to standards like MIL-PRF-38534, which governs not only the end product but also the components, materials, and manufacturing processes. These converters are designed to operate in extreme environments, with features like wide temperature range, hermetic packaging, and resistance to radiation and vibration.

Additionally, military DC-DC converters often feature enhanced reliability features such as wide input voltage ranges, high temperature operation, and ruggedized packaging to withstand harsh operating conditions in the field.

Space-Level Hybrid DC-DC Converters:

In the demanding environment of space, where radiation poses a significant threat to electronic components, space-level hybrid DC-DC converters are a critical component of satellite and spacecraft power systems. These converters must be radiation-tolerant or radiation-hardened to withstand the intense radiation encountered in space. Radiation-hardened components undergo specialized manufacturing processes and materials selection to ensure their resilience to radiation-induced damage, providing reliable power conversion in the harshest of space environments.

Moreover, DC-DC converters are used in various space applications to provide regulated voltage and current source to subsystem. In DC-DC converter, instead of surface mount technology (SMT), hybrid microcircuit DC-DC converters are preferred. For various space applications, HMC DC-DC converters based on thick film technologies offer benefits in size, reliability and cost. The development of thick-film hybrid DC-DC converter for space applications are expected to offer significant growth opportunities to the DC-DC converter market. Furthermore, the development of DC-DC converter with the help of high switching frequency is expected to offer prominent growth opportunities to the global DC-DC converter market. However, DC-DC converter is unable to switch-off during no load condition which is anticipated to be a major factor restraining the growth of the global DC-DC converter market.

Space level hybrid DC-DC Converters, radiation tolerant or radiation hardened, are also governed by MIL-PRF-38534. The manufacturer will have a radiation hardness assurance plan certified by DLA to MIL-PRF-38534 Appendix G. Space level DC-DC converters are available on SMDs and are typically procured to Class K. Space grade DC-DC converters are intended for space applications including satellites, launch vehicles and other spacecraft from low earth orbit to deep space for both commercial and military applications. Typical characteristics of space grade DC-DC converters include:

• Total Ionizing Dose (TID) Radiation. All space applications will require some level of TID radiation guarantee. TID radiation is affected by shielding. For low earth orbits or where the DC-DC converter is adequately shielded, a 30 krad(Si) guarantee is often sufficient. For higher orbits or longer missions, a 100 krad(Si) guarantee may be required. TID erformance should be verified by the manufacturer with component test data or guarantees, worst case analysis, and test data on the complete DC-DC converter. Additional test margin can sometimes be substituted for analysis. Test reports should be available.
• Enhanced Low Dose Rate Sensitivity (ELDRS). TID testing is normally performed at high dose rates to shorten test time and reduce test cost. Testing at lower dose rates, closer to those seen in actual space environments, has shown increased sensitivity to radiation in some components, especially bipolar technologies. Modern space programs will almost certainly have an ELDRS requirement, usually to the same level as the TID requirement. Older DC-DC converter designs may not have an ELDRS guarantee, so be sure to inquire about this. ELDRS performance is proven through testing and analysis.
•  Single Event Effects (SEE). Single event effects are caused by energetic particles which interact with the semiconductors internal to the DC-DC converter. SEE cannot be shielded and must be dealt with in the DC-DC converter design itself. SEE can cause simple transients on the output, dropout, shutdowns and restarts, latch offs or hard failures. Hard failures in a DC-DC converter are often cause by failure of the power MOSFET. An SEE rating of 44 MeV-cm2/mg covers most particles that a spacecraft may encounter in its lifetime and is sufficient for most programs. An SEE rating of 85 MeV-cm2/mg covers essentially all particles spacecraft will encounter during its lifetime. SEE performance is verified primarily with testing of the complete DC-DC converter. Testing should include high temperature latch up testing.
• Worst Case and Radiation Analysis. A guarantee of end-of-life post-radiation performance of the DC-DC converter is usually required. The manufacturer will have completed a detailed worst case analysis for circuit performance including both end-of-life and radiation effects. Radiation degradation of components is fed into analytical and simulation models to predict post radiation performance. Extreme value, root sum square, and Monte Carlo analysis methods are used.
• MIL-PRF-38534 Class K. Space grade DC-DC converters are typically procured to MIL-PRF-38534 class K. Class K includes additional element evaluation and additional screening beyond Class H. Most space level DC-DC converters are procured to an SMD. Procuring to a Class KSMD is less costly than procuring to a custom source Control drawing (SCD).
• No Optocouplers. Although isolation of the feedback control in a DC-DC converter can be accomplished with an optocoupler operating in the linear region, the LED within an optocoupler is sensitive to displacement damage from proton radiation. A reliable space grade DC-DC converter will not use optocouplers. Magnetic feedback, which is insensitive to radiation effects, should be used instead.
•  Aerospace TOR. Some space programs are governed by The Aerospace Corporation report, “Technical Requirements for Electronic Parts, Materials, and Processes Used in Space and Launch Vehicles,” commonly referred to as the “TOR.” The TOR specifies additional quality requirements above and beyond MIL-PRF- 38534 Class K. These requirements can often be met on a custom basis with a modified or modified flow Class K hybrid DC-DC converter. Space level DC-DC converters are specially designed for radiation tolerance. Upscreening by test or even substituting a few radiation hardened components into an existing design will not meet the stringent analysis and testing requirements of modern space programs.

Qualification Standards and Processes:

Both military and space-level DC-DC converters require rigorous qualification processes to ensure their reliability and performance in mission-critical applications. These processes involve testing components, materials, and processes to stringent standards such as MIL-STD-810 for military applications and MIL-PRF-38534 for space-level components. Space-grade converters, also governed by MIL-PRF-38534, undergo additional testing for radiation tolerance and reliability. They are essential for powering satellites, spacecraft, and other space missions, where reliability is critical for mission success. Additionally, adherence to strict quality management systems such as AS9100 ensures that every aspect of the manufacturing process meets the highest standards of quality and reliability.

The military grade DC-DC converter brings several additional characteristics above what you will find in a COTS grade product. These are dictated by MIL-PRF-38534 and they can drastically increase the long term reliability of the system.

A genuine military-grade DC-DC converter adheres to rigorous Mil Spec standards, notably defined by MIL-PRF-38534, the General Specification for Hybrid Microcircuits, regulated and audited by the Defense Logistics Agency (DLA) Land and Maritime, previously known as DSCC under the US Department of Defense. This certification entails thorough scrutiny of components, materials, and manufacturing processes, ensuring adherence to stringent quality benchmarks. Products meeting MIL-PRF-38534 criteria are listed on Standard Microcircuit Drawings (SMDs) and undergo DLA-approved qualifications, guaranteeing reliability from inception. Class H classification within this standard signifies the highest level of quality, making Mil Spec DC-DC converters the preferred choice for mission-critical applications, including avionics, UAVs, ground vehicles, defense systems, and environments with extreme conditions such as high temperatures or high altitudes.

• Wide temperature range. MIL-PRF-38534 class H devices are specified to operate continuously over the full military temperature range of -55°C to +125°C. High temperature operation is enabled with bare die power semiconductors and high thermal conductivity ceramic and metal packaging. True continuous full-power 125°C operation is impossible to achieve with plastic encapsulated ICs and PCB construction. When specifying converters for this temperature range, make sure your supplier does not derate the power at 125°C
• Hermetic Packaging. Qualified hybrid DC-DC converter modules are hermetically sealed, usually in welded metal packages with glass or ceramic seals. Hermeticity protects internal semiconductor devices from moisture related failures. Hermeticity is verified by MIL-STD-883 Method 1014 for fine and gross leak. Internal water vapor is monitored using MIL-STD-883 Method 1018. Hermeticity also allows the device to tolerate liquid cleaning processes during assembly. A true hermetic package should not be confused with packages that appear hermetic, or with datasheets using ambiguous terms such as “sealed” or “near hermetic” that do not meet the hermetic definition of conditions in MIL-STD-883.
• No Pure Tin. MIL-PRF-38534 specifically prohibits the use of internal and external pure tin finishes, with >97% tin, which can produce tin whiskers. Ensure the manufacturer has in place an aggressive program to screen components and eliminate pure tin.
• Component Element Evaluation. All materials and components used in the DC-DC converter module are evaluated in accordance with MIL-PRF-38534 to verify they meet their specifications and are suitable for the intended application. Element evaluation differs from qualification in that it is performed on each lot of material.
• Qualification. True military DC-DC converter modules are qualified in accordance with MIL-PRF-38534. Test methods are dictated by MIL-STD-883. The qualification is reviewed and final approval is given by DLA. This type of qualification differs from that of a commercial manufacturer where the test plan and final approval are selfdetermined. Upon successful qualification, the DC-DC converter can be put on a DLA controlled SMD.
• Qualified Manufacturing Line. The qualified DC-DC converter will be built by a QML listed manufacturer on a qualified manufacturing line. All processes used in the manufacture of the product are qualified and audited by DLA.

At the Mil Spec quality level, some of the characteristics mentioned for COTS products are taken as a given. Manufacturers are certified to ISO-9001 and above that, to MIL-PRF-38534. A counterfeit parts control plan is required. With regard to the products themselves, optocouplers are generally not used at this level, and fixed frequency and full six-sided metal shielding are standard. Mil standard compliance with regard to EMI and input voltage range and transient capability is also standard for this level of product.

Market

DC-DC Converter Market Size was valued at USD 6481.2 million in 2022. The DC-DC Converter Market industry is projected to grow from USD 6857.1 Million in 2023 to USD 12394.6 million by 2032, exhibiting a compound annual growth rate (CAGR) of 6.8 % during the forecast period (2023 – 2032).

Market Drivers

The DC-DC converter market is experiencing robust growth, propelled by various key factors shaping the industry landscape. Firstly, the widespread adoption of electronic devices such as smartphones, tablets, and laptops has surged, driving the demand for compact and efficient power management solutions, thus fueling the market for DC-DC converters. Additionally, the global shift towards renewable energy sources like solar and wind has necessitated the use of DC-DC converters in power optimization, energy storage, and grid integration applications, contributing significantly to market expansion.

Furthermore, the automotive industry’s transition towards electric and hybrid vehicles has led to a substantial increase in the adoption of DC-DC converters for efficient energy management, battery charging, and power distribution within vehicles. Moreover, the expansion of telecommunications infrastructure, particularly in developing regions, along with the rapid deployment of 5G technology, has created a heightened demand for DC-DC converters to ensure stable power supply and efficient signal processing in telecommunications networks. Lastly, advancements in semiconductor technology have facilitated the development of smaller and more efficient DC-DC converter modules, enabling seamless integration into compact electronic devices and systems, thus driving further market growth.

Market Trends

The DC-DC converter market is witnessing several transformative trends that are reshaping its landscape and influencing industry dynamics. Firstly, there is a growing emphasis on high-efficiency solutions driven by the increasing importance of energy efficiency across various sectors. This trend has led manufacturers to prioritize innovative designs and materials aimed at minimizing power losses and maximizing overall efficiency. Secondly, the integration of digital control and monitoring capabilities in DC-DC converters is gaining traction, enabling real-time performance optimization, remote diagnostics, and predictive maintenance. This advancement caters to the evolving needs of industries seeking enhanced reliability and flexibility in their power management systems.

Moreover, the adoption of wide bandgap semiconductor materials, such as silicon carbide (SiC) and gallium nitride (GaN), is on the rise in DC-DC converter designs. These materials offer superior performance characteristics, including higher efficiency, faster switching speeds, and greater power density compared to traditional silicon-based solutions. Additionally, there is a growing trend towards customization and modularization in DC-DC converter solutions to address diverse application requirements. This trend allows manufacturers to tailor products according to specific voltage, current, and form factor needs, providing greater flexibility to end-users.

Furthermore, environmental sustainability is becoming a key focus area for DC-DC converter manufacturers. Sustainability initiatives are driving the development of eco-friendly solutions, with a focus on recyclable materials, energy-efficient manufacturing processes, and reducing the carbon footprint throughout the product lifecycle. This trend reflects the industry’s commitment to environmental responsibility and meeting the growing demand for sustainable power management solutions. Overall, these trends are expected to continue shaping the DC-DC converter market in the coming years, driving innovation and growth in the industry.

Industry

Key companies in the DC-DC converter market are renowned for their expertise and innovation in providing efficient power solutions across various industries. Texas Instruments stands out for its comprehensive range of high-performance DC-DC converters, catering to diverse applications from consumer electronics to industrial automation. Delta Electronics Inc. is recognized for its advanced power electronics technology, offering reliable and energy-efficient converters for telecommunications, automotive, and renewable energy sectors. Vicor Corporation is known for its cutting-edge power modules and systems, delivering superior performance and scalability in power conversion. Mouser Electronics serves as a leading distributor of DC-DC converters, offering a vast selection of products from top manufacturers like Murata Manufacturing Co., Ltd., known for its high-quality and innovative power solutions. General Electric, with its extensive experience in aerospace and defense, provides rugged and reliable DC-DC converters for critical applications. Traco Electronics AG specializes in high-quality, compact converters for medical, industrial, and transportation sectors. Analog Devices, Inc. and STMicroelectronics NV are prominent semiconductor companies offering a wide range of DC-DC converter ICs and solutions. CUI Inc., Cincon Electronics Co., Ltd., and TDK-Lambda Corporation are also key players known for their high-performance converters and commitment to innovation in power electronics. Together, these companies drive advancements in the DC-DC converter market, shaping the future of efficient power conversion across industries.

Conclusion:

As technology advances and the demands of modern applications evolve, the need for specialized power conversion solutions continues to grow. From the efficiency of SMPS to the ruggedness of military DC-DC converters and the radiation tolerance of space-level hybrid converters, each type of power converter serves a unique purpose in meeting the diverse requirements of today’s electronics industry. By understanding the intricacies of these power conversion technologies and the standards they must adhere to, engineers can select the optimal solution for their specific application, ensuring reliability, efficiency, and safety in every power conversion task.