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How to choose small, medium and high power switching power supply module
Release time:
2018-10-29 19:12
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Switching power supply module manufacturers
General parameters
The parameters we need to consider includeVoltage, currentand otherAccessibility. Voltage and current are the two most basic parameters. For example, the power supply is to supply power to the motherboard CPU, which requires 5 volts. The current needs to be calculated according to the system power consumption, such as 5A. Do we choose a 5V/5A power supply in actual purchase? In fact, we will have a certain derating design in the design, generally we choose slightly higher than the actual use of power 20%, so that the power supply work effect is better, reliable and stable, the system is slightly overloaded also does not matter. That is, when selecting power, it is generally 20% larger than the actual power used.
Overall dimension
According to the space of the equipment to choose the power supply, the right is good. Many times we require the smaller the better, but the small size and the high price, so don't blindly pursue small size.
Temperature
Determine the environment in which the power is usedTemperatureSelect the appropriate switching power supply module. The temperature generally given by the switching power supply manufacturer is the shell temperature of the power supply module, such as -25- 85 degrees, then 85 degrees means that the maximum temperature of the power supply shell can reach 85 degrees. If it exceeds 85 degrees, the power supply may enter the protection state or be damaged. When choosing a power supply, you must consider your own ambient temperature and the working efficiency of the power supply. The efficiency is low when the temperature rises, and the efficiency is high when the temperature rises.
Installation method
The module power supply has two packaging forms, one islead pin type, one isTerminal type. The lead pin type can be directly soldered on the PCB printed circuit board. When selecting this power supply, standard products should be selected as far as possible (that is, the lead pin method of each manufacturer is the same, which is easy to replace the manufacturer). If this type of power supply needs heat dissipation, it can be equipped with a radiator (the general manufacturer has supporting products). The terminal type is to use the terminal to connect the power output and the electrical equipment. The power supply can be directly fixed on the housing of the equipment and dissipates heat by means of the housing.
Voltage accuracy
so-calledVoltage accuracyThat is, the voltage stability. The voltage accuracy given by the general manufacturer is about 1%, which indicates a single output. If there are two or three outputs, it only indicates the voltage accuracy of the main circuit, and the voltage accuracy of the secondary circuit is lower. The voltage accuracy of the secondary circuit of multiple products produced by our company is generally in the range of 3%. If the multi-channel output voltage, each voltage accuracy requirements are relatively high, it can not choose such a power supply, but need to choose each independent regulated power supply, each voltage accuracy is relatively high, it is equivalent to multiple power supply to do on a board.
Electrical strength
General electrical strength:
AC Input DC Input
Input to output is 1500VDC/1min/0.5mA Input to output is 1500VAC/1min/0.5mA
Input to enclosure is 1000VDC/1min/0.5mA Input to enclosure is 1500VAC/1min/0.5mA
Output to enclosure is 500VDC/1min/0.5mA Input to output is 500VDC/1min/0.5mA
Reliability
The reliability index is expressed by the average failure-free time MTBF. MTBF has two calculation methods, one is calculated by long-term statistics, and the other is calculated by the method specified in the MIL-HDBK-217F2(GJB299) standard, that is, MTBF = 1/λ. The calculation method is very complicated. The most important thing is to obtain the value of λ, which is related to the following items: A. ambient temperature B. operating environment c. number of components d. grade of components e. derated redundancy.
ripple characteristics
At present, the ripple parameters given by the power supply manufacturer are based on the YD/T1376 standard, usually 1% Vout. For example, the ripple of 5V output voltage is not higher than 50mV, and the ripple of 12V output voltage is not higher than 120mV, which may not be enough for analog circuits, so the ripple problem should be fully considered when selecting the power supply. However, when measuring with an oscilloscope with a bandwidth of 20M, it is more accurate to use the method of measurement, and cannot be measured with a ground clamp, otherwise the ripple data of the test will be very large.
Range of input voltage
At present, the input (DC) range of most manufacturers is 2:1 ratio input, that is, 5V(4.5-9V) 12V(9-18V) 24V(18-36V) 48V(36-72V)
Delivery date
When ordering products, we must master the production cycle of the manufacturer so as not to delay the production time, which is self-evident.
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2019-08-06
Product selection and application considerations
The design power of each product of our company will have a certain amount of redundant power, which can run for a long time under full load or even over the rated load. However, for the sake of high reliability and prolonging the service life of the power supply, please do not let the load reach the rated value. It is generally recommended to use 60%-80% of the rated load, and the ambient temperature is recommended to be about 30 ℃, which can be fully loaded at an ambient temperature of 55 ℃, but this will undoubtedly greatly reduce the reliability and service life of the product. In actual use, please pay attention to the two factors of controlling load and temperature. If the ambient temperature is relatively high, it is necessary to reduce the load as much as possible (that is, to increase the load margin and select products with greater output power). On the contrary, if a large load current is required, then try to do a good job of ventilation and heat dissipation, such as placing the power supply module in an open space and increasing cooling fans. The specific value is not absolutely fixed. Generally, it is recommended that the load should not exceed 20% of the rated load when the ambient temperature is 55 ℃, which can keep the product very high reliability. Tip: Please use temperature measuring equipment to evaluate the temperature, and do not rely on skin feeling. Short time and a small proportion of full load, high temperature operation, the reliability and life has little effect. For example: each full load lasts less than 1 minute or half a minute, and the interval is more than 10 minutes, while the load during the interval is less than 15% of the rated load, then even if the operation at 55 ℃ is also possible. Safe Use Warning: Since the bare board series does not have a shell, the input is 220V AC at the same time. The input pins and corresponding terminals of the module are directly connected to 220V. Please pay great attention to prevent short circuit between electric shock and metal objects and ensure that the power supply is disconnected before any touch. Load Requirements for 2. Use of Multiple Output Power Supplies Generally, the voltage accuracy of the output of the multi-output power supply is: the nominal value of the main output is plus or minus 1%, and the nominal value of the secondary output is plus or minus 5%-10%. The first output of the multi-output power supply is the main circuit, and the other output is the secondary circuit. The voltage accuracy and carrying capacity of the main circuit are higher than those of the secondary circuit. Therefore, the main circuit with large current and high voltage accuracy requirements should be generally selected, it is appropriate that the ratio of each current is 50-100%, and the secondary circuit must not be loaded separately under the condition of no load on the main circuit, otherwise the secondary circuit voltage is too low to be used normally. In addition, if the main circuit load is full load and the secondary circuit load is light load, the secondary circuit voltage may increase, otherwise the secondary circuit voltage will decrease, and the reliability and service life will have little effect. For example, if each full load lasts less than 1 minute or half a minute, and the interval is more than 10 minutes, while the load during the interval is less than 15% of the rated load, then even operation at 55°C is possible.
2018-08-29
Application field of switching power supply module
Switching power supply module is applied in several major aspects 1. Electric power, mainly including integrator and electric meter and intelligent electric meter 2. Industrial control, industrial control field 3. Medical treatment, medical equipment, mainly including tire protection instrument, monitor and so on 4. Military industry, military industry is a very widely used aspect. in military equipment. Switching power supply module applications in several major areas.
2018-08-29
Precautions for the use of switching power supply modules
The high-frequency transformer of switching power supply is generally shielded for the first time, which is not described above. Switching power supply is a high-frequency product, PCB component layout for EMI, please pay close attention to this point. If the switching power supply has a mechanical shell, the structure of the shell has a great influence on the radiation, please pay close attention to this point. The parameters of different manufacturers of the main switch tube and the main diode have certain differences, which have certain influence on EMC. Please pay close attention to this point.
2018-08-29
Can switching power supply and module power supply be universal?
A module power supply is a power supply that can be mounted directly on a printed circuit board and is characterized by providing power to application-specific integrated circuits (ASICs), digital signal processors (DSPs), microprocessors, memory, field programmable gate arrays (FPGAs), and other digital or analog loads. In general, such modules are called point-of-load (POL) power supply systems or point-of-use power supply systems (PUPS).
2018-08-29
The difference between switching power supply and module power supply
(1) The difference in use: module power supply, output voltage, remote control switch circuit, input protection circuit. Switching power supply, control the switch tube on and off time ratio, maintain a stable output voltage of a power supply. (2) The difference in composition: Switching power supply: Generally composed of pulse width modulation (PWM) control IC and MOSFET. Module power supply: it is composed of power supply module with a small amount of discrete components.
2018-10-19
Loss of switching power module
The loss of high-power module switching power supply mainly includes high-frequency switching loss, high-frequency transformer loss, rectifier loss and line conduction loss. In the application of low voltage and high current output, the rectifier loss and line conduction loss occupy a larger proportion, the lower the output voltage, the greater the output current, the rectifier loss and line conduction loss accounted for the proportion of the total loss of the module switching power supply.
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