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What is a power module?
A power module is a power converter that can be directly soldered onto a circuit board. It is generally divided into AC to DC or DC to DC based on the conversion method.With the development of technology, power modules are becoming more modular and compact, leading to the emergence of power modules.It has the highest integration, integrating the main circuit of the switching power supply into the chip circuit, enabling wide frequency modulation, isolation, and various protection functions.
The common basic principles consist of the following components: input rectifier filter, including rectifier bridge and input filter capacitor.A single-chip switching power supply, including power switch tube, controller, and MOSFET.There are also high-frequency transformers, leakage clamp protection circuits, optocoupler feedback circuits, output rectifier filter, bias circuits, and other components.
The power module can generally adapt to an input voltage range of AC 85-265V or DC 100-370V through the input rectifier filter, with a frequency selection of 47-400Hz, typically 50/60Hz.Due to its compact size, high integration, cost-effectiveness, and optimal performance metrics, it requires only the simplest peripheral circuits and a small number of discrete components.Moreover, it has advantages such as high efficiency, high reliability, and flexible design, making it the preferred integrated circuit for developing and designing small power switching power supplies.
The technical requirements for selecting power module solutions are low, the design is simple, occupies little space, has high reliability, and can be changed at any time.When product design needs to be modified, it is sufficient to connect in parallel or replace the power module.Therefore, it is widely used in various fields such as industrial control, machinery, ships, aerospace, communication, military, data communication, handheld electronic products, instruments, LED lighting, intelligent systems, electric power, railways, security, mining, medical, automotive electronics, and more.
Currently, it is almost impossible for a single power module to pass EMC tests such as SURGE, EFT, CE, RE, etc. Although foreign products have a long lifespan, high reliability, and good EMI control, their anti-interference performance is still not strong enough.Most switching power supplies pass UL and 3C certification, ensuring EMI performance, but modularization fails due to the method of testing EMI. To allow devices to pass EMC testing, good peripheral circuit design is necessary.
It is best to choose a power module with a power range of 30-80% of the required usage; generally, this power range exhibits stable and reliable performance.The classification mainly includes commercial grade, industrial grade, and military grade, with different levels having varying requirements for operating temperature, vibration, humidity, etc.To ensure long-term stable and reliable operation of the product, it is necessary to consider the actual application environment when selecting products.
How to choose a high-reliability DC-DC power module
Nowadays, DC-DC power modules are increasingly applied in industries such as communication, industrial automation, power control, military, etc.The modular design can effectively simplify the customer’s circuit design and enhance system reliability and maintenance efficiency.So, how to choose a high-reliability DC-DC power module?
1. Use mature power topologies
First, use mature power topologies.When designing power modules, it is advisable to select mature power topologies that have stood the test of time and are reliable.For example, for 1-2W constant voltage input DC-DC power modules, the Royer circuit is chosen, while wide voltage input series often select Flyback topology or some Forward topologies.
2. High efficiency across the entire load range
Secondly, high efficiency across the entire load range.High efficiency means lower power loss and lower temperature rise, which can effectively improve reliability.In practical applications, power supplies often choose a certain degree of derating design, especially as the power consumption of load ICs continues to decrease today, power supplies may often operate under light load conditions.Thus, high efficiency across the entire load range is a critical parameter for the reliability of power systems.
3. Extreme temperature characteristics
Additionally, extreme temperature characteristics are also very important.Because power modules are applied in a wide geographical range, they may face tropical heat as well as the severe cold of Russian winters.Therefore, the working temperature range for DC-DC modules should be at least -40 degrees to 85 degrees; if used in automotive BMS or high-voltage bus monitoring applications, the working temperature should range from -40 degrees to 125 degrees.Extreme temperature testing is the most effective way to verify the reliability of power modules, including high-temperature aging, high-temperature & low-temperature live operation performance tests, high-low temperature cycling shock tests, and long-term high-temperature high-humidity tests.Standard power development will undergo the above tests.
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