The universal power adapter is also called an external power supply. It is a power supply voltage conversion device for small portable electronic devices and electronic appliances, which is commonly found in small electronic products such as mobile phones, liquid crystal displays, and notebook computers.
What is the meaning of the nominal voltage and current of the universal power adapter (hereinafter referred to as the power supply)?
First of all, the nominal voltage of the general power supply refers to the voltage of the open-circuit output, that is, the voltage when no external load is connected and there is no current output, so it can be understood that this voltage is the upper limit of the power supply output voltage. In the case where an active voltage regulator is used inside the power supply, even if the mains voltage fluctuates, its output is a constant value. Like a small transformer on the market, such as a power supply with a Walkman, if the mains fluctuates, The output of this power supply will not fluctuate accordingly.
Generally speaking, the true no-load voltage of a universal power adapter is not necessarily the same as the nominal voltage. Because the characteristics of electronic components cannot be completely consistent, there is a certain error. The smaller the error, the higher the consistency requirement for electronic components, rendering higher production cost, and ultimately more expensive price. In addition, regarding the nominal current value, any power source has a certain internal resistance, when the power supply output current, there will be a pressure drop inside, resulting in two things, one is to generate heat, so the power supply will be hot, and the other is to cause the output voltage to drop, which is equivalent to internal consumption.
The power supply is the same nominal voltage, the output current is different, can it be used on the same notebook?
The basic principle is that a large nominal current source can replace a small nominal current source. It is estimated that some people will think this way, think that the power of the large nominal current will burn out the books because the current is large. In fact, how much current depends on the load when the voltage is the same, you will know thinking about the physics of junior high school. When the notebook is running at a high load, the current is larger. When the notebook enters standby mode, the current is smaller, and the power source with a large nominal current has sufficient current margin. On the contrary, there is no problem in using a 56w power supply instead of the 72w. The reason is that the design of the universal power adapter usually has a certain margin, and the load power is less than the power supply, so this replacement is feasible in general use. However, the remaining power supply margin is very small, once your notebook has a lot of peripherals, such as two USB hard drives, then the CPU runs at full speed, and then add a base and a CD-ROM full-speed read disk to it, plus charging the battery is estimated to be dangerous. Therefore, it is best not to use a small current source instead of a high current source.
A suitable universal power adapter is required to have a safety certification. A safety-certified universal power adapter can prevent electric shock, fire, and other dangers.