AC-DC medical power of selection criteria and the typical application scenarios (1)

Medical device industry is related to human life and health of the emerging industry, the past decade, the world's developed countries has maintained a very high rate of growth of the market, and, therefore, was hailed as a sunrise industry.

With the medical standards, more and more advanced medical equipment widely used in a variety of medical applications. Power as an important component of the medical device, it is relative to other types of power products include more stringent requirements. This article focuses on the medical supply of special requirements, and Kim Seung Yang company high quality medical products with AC-DC. technical characteristics

Particular requirements for medical power supplies

At present, most of the medical equipment of switching power supply.

With the development of electronic technology, switching power supply not only the volume significantly smaller, lighter, and significantly reduce energy consumption and improves reliability. Use the AC power supply for medical diagnosis, measurement and treatment equipment, may be due to improper grounding and electrical insulation, leakage current generated so that patients and medical personnel exposed to electric shock, burn injury, internal organs and arrhythmia, and other potential danger.

In view of the medical equipment of special environmental, medical supply products in the security and reliability have more stringent requirements.

For example, must meet safety IEC60601-1 insulation and leakage current requirements, or their related standards, such as: EN60601-1, UL60601-1 and CSA22.2 No. 601.1 M90 standards. Table 1 summarizes the IEC 60601-1 medical device safety requirements.

Table 1 IEC60601-1 safety standards requirements

On the one hand, medical device electromagnetic radiation and electromagnetic radiation protection is an important medical power supply parameter standard involves a power surge and transient current strength, electrostatic discharge (ESD) level, and radio frequency interference (RFI) protection capability.

Many medical applications involving RF apparatus or non-invasive electronic surgical instruments, so the power supply must be protected against interference, are not affected.

Qualified medical power supply shall meet the relevant technical requirements of the EMC compatible EN60601-1-2 standard.

Moreover, the medical power supply also must meet IEC61000-4-2 (ESD capacity requirements meet 3kV), IEC61000-4-3 (radiofrequency radiation protection capabilities to 3V/m), IEC61000-4-4 EFT (voltage transient capacity requirements meet 1kV), IEC61000-4-5 (AC surge capacity to 1kV and 2kV), IEC61000-3-2 (power line harmonics), IEC61000-3-3 (power line flicker requirements), as well as EN55011 (A type of product or B product emission limits) and other requirements.

In addition, related to specific applications and some special requirements, for example, you may want to use in the ambulance, voltage shock can occur, this power should at least conform to IEC 68-2-29; some devices is a portable device, you may use in helicopters, and thus appear random vibration, this kind of power supply shall meet the standard MIL-STD-810E.

Kim Seung Yang LD series product characteristics

Kim Seung Yang company committed to the health development with ACDC power, currently owns LD05, LD10 series products, products of principle diagram shown in Figure 1.

Products in the design process to high reliability as the goal, in the design of each link is reflected.

Figure 1 schematic diagram of LD series products

First, product control chip reliability on product reliability are essential.

Our product selection on semiconductor company of PWM control chip, chip features a very powerful, you only need to add a few elements to form complete switching power supply, thus greatly simplifies the design of the product, in a sense also greatly improves the reliability of the product. In addition, the chip's standby power consumption is very low and is able to provide consistent with United States energy star and European sky enables standard solution, no State can be reached at the International Energy Agency (IEA) latest recommendations. Chip short-circuit protection feature is able to continuously monitor the status of the feedback line, a short circuit is detected, and immediately reduce the output power, and of the overall power supply circuit protection after class. Once the short circuit is gone, the controller will return to normal work. This feature is also greatly improved the product in the exceptional conditions of reliability.

Secondly, in the thermal design power supply module we also did a lot of useful research.

MTBF is the power supply reliability of quantitative indicators, and the impact of the most important factors in MTBF is part of the temperature. Therefore to increase the reliability of power supply, how to maintain a relatively low temperature is critical. Simulation methods help to some abstract become more intuitive, so we introduced the electric model. The so-called electric simulation is used for thermal electric circuit to simulate the thermal circuit of electronic components, electrical parameter simulation of heat transfer. Specifically, that is, the current in a circuit used to simulate the thermal circuit of the heat (computing, common dissipation power semiconductor devices instead of heat Q PD), current flows to represent the transmission of heat flow. Voltage U corresponds to the device temperature difference between the ambient temperature, the resistor R ¡÷ T equivalent thermal resistance Rth. Of course, in addition to the simulation of heat transfer, in the design and verification process, a large number of high-temperature reliability test is also used to verify and improve thermal design of the product.