1. The real cause of constant voltage power supply failure
Applications using RS485 and CAN communication, as well as operational amplifiers, inevitably require a type of power module: a 1-2W fixed voltage input power module. These modules mostly employ mature push-pull (Royer) circuits, characterized by simple and mature circuit topologies and high manufacturability. Consequently, some small, family-run workshops manufacture these modules and sell them at extremely low prices. While the purchase cost of such power modules appears very low, the price of a single product does not reflect its true cost. Low-reliability products are prone to failure, and the costs of dispatching engineers to the site and the resulting loss of customer trust will far exceed the user's expectations. Therefore, an extremely low defect rate is a potential and necessary requirement for many high-end customers.
On the other hand, common 1-2W constant voltage power supply modules often fail due to low efficiency under light loads, excessive capacitive loads, or occasional output short circuits. Worse still, most failure modes are input short circuits caused by the breakdown of the input switching transistor. A short circuit at the input port of the power supply module will pull down the voltage of the pre-amplifier power supply, causing the entire system to crash. Even more seriously, if the pre-amplifier power supply has a strong power supply capacity and an excessively large overcurrent protection point, the failure of constant voltage products often leads to serious problems such as the burning of the entire PCB board or even a fire. Therefore, the inherent defects of Royer circuits are increasingly unable to meet the high reliability requirements of modern systems.
So where exactly is the solution to the failure propagation issues of low efficiency under light loads, excessive output capacitive loads, and output short circuits?
2. Who says you can't have your cake and eat it too?
How to maintain high-efficiency conversion, achieve output short-circuit protection, and improve the long-term reliability of power modules has become an industry challenge for 1-2W constant voltage power modules.
Mornsun, a leading company in the field of low-power module power supplies, has consistently maintained an internationally leading position in low-power power supply technology research. Despite being an industry leader, Mornsun has also encountered the aforementioned industry challenges in product development. To thoroughly solve these inherent problems of 1-2W constant voltage power modules, Mornsun has invested heavily in R&D, creatively proposing six patented technologies. These technologies fundamentally solve inherent technical problems of Royer circuits, such as lack of output short-circuit protection, low efficiency under light load conditions, susceptibility to failure under long-term no-load conditions, poor capacitive load capacity, poor high and low temperature characteristics, and excessively large isolation capacitors. Furthermore, our R2 generation product is the only constant voltage product in China to have undergone system reliability engineering modifications. We have adopted DFMEA and PFMEA measures, comprehensively improving and enhancing reliability from the failure mechanism level, component level, manufacturing process level, and customer application level. We have also invested significant resources in component characteristic optimization, PCB layout optimization, production process improvement, and quality control to comprehensively improve product performance and quality. The theoretical failure rate of the product has been reduced from 300ppm in the first-generation power modules to 30ppm in the current R2 generation, significantly reducing customer operating costs and improving system reliability. Currently, Mornsun's constant voltage R2 generation power modules are the only products globally that simultaneously feature long-term output short-circuit protection, high efficiency across the entire load range, excellent EMI characteristics, low ripple noise, and superior high and low temperature performance. Mornsun has elevated the technological level of constant voltage products globally to a whole new level.
3. Nine core selling points establish an absolute advantage.
Through a series of systematic reliability engineering improvements, the overall performance of Mornsun's R2 generation constant pressure products has been greatly improved compared to the previous generation. This comparison is based on Mornsun's three generations of products, B0505LS-1WR2, B0505LS-1WR, and B0505LS-1W, as shown in Table 1.
Table 1. Comparison of advantages between the second-generation and first-generation constant pressure R2 products.
As can be clearly seen from Table 1, Mornsun's R2 generation products not only achieve long-term short-circuit protection, but also have made breakthrough improvements in all key performance aspects.
1) High efficiency
Current power modules using conventional Royer circuits exhibit extremely low conversion efficiency under light load conditions. However, in practical applications, prolonged operation under light loads can lead to module failure due to low conversion efficiency, and even system collapse. Mornsun's R2 generation products represent an innovative upgrade from the first generation, significantly improving efficiency, particularly under light loads. The R2 generation achieves twice the conversion efficiency of its predecessor. Figure 1 compares the efficiency curves of Mornsun's first-generation B0505LS-1W and B0505LS-1WR power modules with the R2 generation B0505LS-1WR.
Figure 1. Efficiency Comparison Curves of R2 Generation Products
As can be seen from the figure above, under full load conditions, the conversion efficiency of the R2 generation product is improved by about 10% compared with the original product. However, under light load (5% load) conditions, its efficiency has increased from the original 22% to about 40%, which more effectively ensures the reliability of the product when working in the system under light load conditions for a long time.
2) High temperature characteristics
Thanks to its improved efficiency, advanced manufacturing processes, and the use of internationally renowned raw materials, the product has undergone reliability improvements in areas such as ESD, MSD, welding reliability, and lean manufacturing. This has significantly enhanced the product's stability and reliability. Its operating temperature range meets military standards, ranging from -40℃ to 105℃, greatly reducing the likelihood of high-temperature failures in application environments. In contrast, Mornsun's first-generation products only met the operating temperature requirement of -40℃ to 85℃, which could easily lead to product failure in high-temperature environments, severely limiting the design and application requirements of the customer's entire system. Figure 2 shows its operating temperature curve.
Figure 2 Operating temperature curve of constant pressure product
As can be seen from Figure 2, the first-generation Mornsun product cannot be used normally when the operating temperature reaches 105℃, and it cannot meet the requirements of systems with high working environment. However, the R2 generation Mornsun product can solve this problem well, and the system's application environment and reliability are greatly guaranteed.
3) Long-term short circuit protection
Power modules with long-term output short-circuit protection are an important indicator of overall system reliability. However, conventional Royer circuits do not have this feature. When an output short circuit occurs, the input switching transistor of the power module will break down, causing an input short circuit and leading to the collapse of the upstream power supply. More seriously, if the upstream power supply lacks overcurrent protection or has an excessively high overcurrent protection point, it may cause serious problems such as fires.
To address the output short-circuit protection issue of voltage products, a common industry practice is to utilize transformer winding separation technology to achieve long-term output short-circuit protection. However, this approach significantly reduces product conversion efficiency, sacrifices ripple noise characteristics, and increases costs.
By utilizing Mornsun's own patented technology, Mornsun's R2 generation products not only achieve long-term output short-circuit protection but also meet the requirements for high efficiency across the entire load range.
4) High capacitive load
In electronic systems, some specialized components inherently possess significant capacitive reactance. To reduce power module ripple noise, external large capacitors are often used for filtering at the output, requiring the power module to have a high capacitive load capacity. However, conventional constant-voltage power modules designed with Royer circuits have very weak capacitive load capacity, typically only achieving around 10uF. Excessive output capacitors or the use of tantalum capacitors for filtering can cause startup problems or even product failure. Furthermore, most system designers only focus on the module's capacitive load capacity at room temperature, while practical applications require a temperature range at least as low as -40℃. Therefore, the overall capacitive load capacity at low temperatures is a more critical reliability issue.
Mornsun's R2 generation products not only provide long-term short-circuit protection, ensuring the safety of the power module itself when tantalum capacitors are used for filtering, but also achieve a capacitive load capacity of hundreds of microfarads, greatly improving the system's ability to withstand the capacitive load of the power module and relaxing the requirements for selecting subsequent capacitors.
5) Stable light load characteristics
Currently, in order to achieve high reliability requirements, system designers often adopt significant power derating in the use of power modules. This requires the power modules to meet the stability and reliability requirements under light load conditions. However, the constant voltage power modules implemented using conventional Royer circuits in the industry have low conversion efficiency under light load conditions, resulting in high light load losses and increased product temperature. In multi-module applications or enclosed environments, this may lead to a relatively high failure rate, which completely fails to meet the application requirements for high reliability.
Mornsun's R2 generation products feature upgrades in both circuitry and manufacturing processes, ensuring efficiency, stability, and reliability under light load conditions, allowing customers to truly experience the convenience of highly reliable products.
6) Low isolation capacitor
In power supply design, especially in power module products implemented using conventional Royer circuits, large-capacity Y capacitors are often used between the primary and secondary windings to achieve low high-frequency switching noise. Furthermore, conventional transformers also have significant interlayer capacitance between windings, resulting in excessively large isolation capacitance within the power module itself. However, in electronic systems, this isolation capacitance issue significantly reduces the system's common-mode interference immunity, leading to frequent malfunctions.
To achieve low isolation capacitance, Mornsun's R2 generation products address issues in transformer design and EMI design, eliminating the need for excessively large external Y capacitors between the primary and secondary windings. This reduces high-frequency noise caused by high-frequency switching, resulting in extremely low isolation capacitance and providing a more reliable guarantee for the system to effectively resist common-mode interference.
7) EMI & EMC characteristics
EMC performance is essential for the normal and safe operation of electronic systems. Currently, the electronics industry places high demands on the EMC performance of its products. As a core component of electronic systems, the EMC performance of power modules directly impacts the overall system performance. Therefore, high EMC characteristics are a critical issue in power module product design. However, in constant voltage power modules, due to limitations in size and cost, the EMC characteristics of products in the industry, including Mornsun's first-generation products, are unsatisfactory, severely affecting the overall performance of electronic systems. System designers need to add excessive EMC components before and after the power module to meet basic EMC requirements. For example, Mornsun's first-generation products require complex external circuitry to meet CLASS B EMI requirements, and only meet the 4KV electrostatic discharge (ESD) test requirement.
To achieve high EMI performance requirements, Mornsun has comprehensively upgraded and improved the EMI characteristics of its R2 generation products. With the addition of a few external components (using a Π-type filter at the input), it can meet the EMI level requirements of CLASS B, and its electrostatic discharge level can also reach the standard of 8KV, greatly improving the EMI & EMC characteristics of the product. Figure 3 shows the conducted conductivity test results after adding a few external circuits.
Figure 3. EMI test waveform of constant voltage R2 generation product
8) Excellent assembly experience
Mornsun's first-generation products use a plastic shell potting process similar to that used in the industry. The difficulty in this type of product lies in the poor accuracy of the distance between the pins and the shell. When large-scale automated operations are carried out, the production and maintenance costs caused by the pin pitch accuracy problem will increase significantly, causing additional economic losses to the customer's production.
Taking Mornsun's B0505LS-1WR2 generation product as an example, this product adopts advanced plastic encapsulation technology in the industry, which greatly shortens the product production cycle, ensures high precision of pin spacing and housing, and can fully meet the requirements of automated mechanical plug-in production process, bringing great convenience to customers' mass production and reducing customers' assembly costs.
9) A complete system guarantees
Mornsun is currently the only power module manufacturer in China to have passed TS16949 automotive product certification. Compared to the ISO9001 standard, TS16949 places greater emphasis on process control and FMEA analysis. Mornsun not only possesses automotive-grade dedicated power modules, but also gradually extends the quality management requirements of automotive product certification to the development and production of its R2 generation products, more effectively ensuring the reliability and stability of its R2 generation power module products.
Currently, Mornsun's R&D system integrates IPD product development specifications, ISO9001 product development requirements, TS16949 design control requirements, reliability platform requirements, and full-process target cost management, creating a unique Mornsun-style R&D management system that provides a reliable system guarantee for creating high-quality products.
3. Summary
Through continuous technological research and production process improvements, Mornsun's R2 generation products have achieved significant enhancements in both basic electrical performance and reliability. This upgrade process has resulted in numerous patents. Furthermore, due to process improvements and expanded production scale, the company has successively introduced automated PCB placement equipment, automated transformer winding equipment, automated finished product testing equipment, and automated marking equipment, reducing labor and manufacturing costs and ensuring high cost-effectiveness. Mornsun's R2 generation power modules lead other similar power module products with absolute advantages. As a national enterprise, Mornsun is competing with internationally renowned brands overseas, becoming a world-class power supply brand. In particular, its technological innovations in constant voltage power modules have propelled the industry forward significantly, achieving a revolutionary upgrade to Royer circuits and making an indelible contribution to the development of the power module industry.
