The design concept, product process, testing methods, and materials are controlled by the power module manufacturer, while how they are used is controlled by the customer. From the manufacturer's perspective, engineers should optimize various indicators as much as possible during product research and development to ensure high product reliability.
Product manufacturing processes refer to the procedures during production and storage that do not affect product quality. For example, neglecting electrostatic discharge (ESD) protection during power supply production may increase component damage rates, thus affecting the power supply's lifespan and reliability. Storage should include protection against moisture, extreme temperatures, and static electricity.
The system's testing methods can detect problems before they occur, preventing damage to the equipment during use. Because a power supply is an integrated circuit, the quality of its components is crucial; good components naturally result in good quality. Customers typically consider the impact of the operating environment and temperature on the product, but ultimately, the manufacturer controls the product's temperature range.
The Importance of DC-DC Module Power Supply
DC-DC isolation modules play a crucial role in distributed power systems. They not only effectively isolate common-mode interference from primary-side devices, ensuring stable load operation, but also perform voltage conversion, regulation, and protection. In various application scenarios, different loads require different supply voltages, and DC-DC isolation module power supplies are perfectly suited to meet these needs.
The function of DC-DC isolation module
Furthermore, due to line losses during long-distance transmission of bus voltage, the PCB-level voltage drops. Since the load requires a stable voltage to operate normally, wide input voltage range and regulated output voltage are essential. Additionally, in abnormal conditions, the power supply must also have the capability to protect the system load and itself from damage.
Choose a high-reliability power supply
So, how do you choose a high-reliability DC-DC power supply module? The key lies in using a mature power supply topology. For example, for 1W to 2W constant-input DC-DC power supply modules, a Royer circuit can be chosen; while for wide-input series, Flyback topology is often chosen, and Forward topology is used in some cases. Furthermore, high efficiency across the entire load range is also indispensable. High efficiency means lower power loss and lower temperature rise, thereby effectively improving the reliability of the power supply system.
In practical applications, power supplies typically employ a certain degree of derating. Especially today, with increasingly lower power consumption of load ICs, power modules often operate under light load conditions. Therefore, high efficiency across the entire load range is crucial for ensuring the reliability of the power system. Unfortunately, this is often overlooked by some power supply manufacturers. In pursuit of attractive specifications in their technical datasheets, they may overemphasize full-load efficiency while neglecting light-load efficiency.
Taking Mornsun's 15W DC-DC modular power supply VRB2412LD-15WR2 as an example, this product achieves 15% higher efficiency than mainstream competitors at a light load of 10% with a rated input voltage of 24V. This advantage plays a crucial role in improving the reliability of power supply systems.
Power supply applicability under extreme conditions
Extreme temperature characteristics
The application environments for power modules vary greatly, ranging from the high temperatures of the tropics to the frigid conditions of Russia. Therefore, DC-DC modules must have a wide operating temperature range, from -40℃ to 85℃. Mornsun's constant voltage R2 generation 1W-2W modules can even achieve excellent performance of -40℃ to 105℃. For applications such as automotive BMS or high-voltage bus monitoring, even higher operating temperatures are required; for example, Mornsun's CF0505XT-1WR2 can reach 125℃.
Extreme temperature testing is crucial for verifying the reliability of power modules. This includes high-temperature aging, high and low temperature live-line performance testing, high and low temperature cycling shock, and long-term high-temperature and high-humidity testing; all of these are essential steps in the development of a legitimate power supply. Therefore, the availability of such testing equipment is an important indicator of a power supply manufacturer's professionalism.
High isolation, low isolation capacitors
Medical and power electronics products have specific requirements for power modules. Medical products require extremely low leakage current, while power electronics products require minimal primary and secondary parasitic capacitance. Both fields emphasize high isolation voltage and low isolation capacitance to reduce the impact of common-mode interference on the system. When selecting modules, it is recommended that the isolation capacitance of 1W to 2W DC-DC modules be less than 10pF, and for wide-voltage products, modules with an isolation capacitance of less than 150pF should be selected.
EMC and Application Design
The Importance of EMC Performance
Excellent EMC performance is the cornerstone of the normal and safe operation of electronic systems. As the electronics industry continues to demand higher EMC performance, the EMC characteristics of power modules have become a key factor in their core competitiveness. Any system reset, restart, or premature failure caused by improper EMC handling will seriously affect product market performance and customer satisfaction.
System application design strategy
Besides the reliability of the power supply itself, system application design is equally crucial. Due to the complexity of the operating environment of power systems, even the most reliable power supply can fail due to a lack of reliable system application design. Therefore, various methods and techniques need to be employed in power system application design to ensure system stability and reliability. Among these, redundancy design is an important strategy, which improves the system's fault tolerance and stability by adding redundant components or designing redundant circuits.
In applications requiring high reliability, the stability of power modules becomes crucial, as it directly impacts the overall system operation. To ensure the system remains powered even in the event of a power module failure, a common solution is to employ a redundant power supply design. This design allows the system to continue operating through the backup power of another module if a single power module fails.
Heat dissipation and PCB design
In addition, derating is an effective way to improve the lifespan of a power supply. However, excessively light loads will prevent the power supply from reaching its optimal performance. For example, Mornsun DC-DC power supplies perform best when used within a load range of 30% to 80%.
In power module applications, proper design of peripheral circuitry is also crucial. Due to the general-purpose design of DC-DC power modules, they may not meet the requirements of certain demanding application environments. Therefore, when customers have specific application requirements, it is necessary to add appropriate peripheral circuitry to improve the reliability of the power supply.
Thermal design is also a crucial aspect of industrial-grade power modules. Approximately 15% of power module failures are due to poor heat dissipation. In power modules operating continuously in enclosed environments, if heat cannot dissipate, internal components may be damaged due to exceeding thermal stress. Therefore, appropriate heat dissipation measures, such as natural air cooling, heat sinks, or reinforced cooling fans, are necessary to ensure stable operation of the power module.
Regarding thermal design, there are some experiences worth sharing. First, ensure the environment around the power module facilitates convection ventilation and is free of large obstructions to allow for airflow. Second, if there are multiple heat sources in the system, such as multiple power modules, they should be kept at a certain distance to avoid heat radiation transfer between them that could lead to overheating. Following these guidelines can further improve the reliability of the power module.
In the field of power module design, many customers require products to have high reliability. To ensure that power modules can operate stably under various complex environments and application conditions, how can this be achieved? This article will discuss how to consider and optimize from multiple dimensions, hoping to be helpful to our readers.
Surge protection circuit design
Surge currents can damage components in circuits; therefore, designing a properly designed surge protection circuit is crucial. When designing a surge protection circuit, the positions of components such as inductors and TVS diodes need to be adjusted according to different application scenarios to improve the system's EMC performance. At the same time, attention should be paid to the design of a two-stage surge protection circuit to ensure that it effectively protects the circuit while avoiding negative impacts.
Reduce design volume
By precisely calculating and controlling the number of components within a reasonable range, system complexity and failure rate can be reduced. Simultaneously, reducing the number of components can lower production costs and improve production efficiency. During the design process, the use of excessive redundant components and complex circuit structures should be avoided as much as possible to ensure system stability and reliability.
Dual power supply module design
In the design of bidirectional power modules, attention should be paid to the even adjustment of the output of the main and auxiliary circuits to ensure load balance. This design allows the other power module to continue operating even if one power module fails, thus ensuring the stable operation of the entire system. Furthermore, the dual power module design can improve the system's flexibility and scalability, meeting the needs of different application scenarios.
Component selection
The application of different components will have varying impacts on module performance. Therefore, when selecting components, factors such as performance, reliability, and lifespan must be fully considered. For example, when choosing capacitors, ceramic or electrolytic capacitors are common choices, but tantalum capacitors, while offering long lifespan, high-temperature resistance, and good performance, also pose a risk of circuit breakdown. Therefore, component selection requires a trade-off based on the specific application scenario and requirements.
Power supply safety and reliability mean that the power supply will not malfunction or cause danger during use, ensuring the safety of users' bodies and property. The following requirements need to be considered in power supply design:
1. Over-temperature protection requirements: The power supply should not overheat when outputting rated power. It should be designed with over-temperature protection function to prevent the power supply from overheating and causing failure.
2. Overvoltage protection requirements: The power supply should be designed with overvoltage protection function when the output voltage exceeds the specified range in order to avoid damage to the product and users.
3. Overcurrent protection requirements: When the output current exceeds the specified range, the power supply should be designed with overcurrent protection function to avoid damage to the product and users.
4. Short circuit protection requirements: The power supply should be designed with short circuit protection function when the output is short-circuited in order to avoid damage to the power supply and the product.
In conclusion, power supply design is a crucial part of electronic product development, requiring consideration of multiple aspects such as power supply stability, efficiency, and reliability. Only by designing a high-quality, reliable power supply can stable product performance and user experience be guaranteed.
