AC DC Power Adapter Problems and Precautions

The AC/DC power adapter is a power supply conversion device for small portable electronic devices and electronic appliances. It is generally composed of a casing, a power transformer and a rectifier circuit. According to its output type, it can be divided into an AC output type and a DC output type and desktop power supply.

What is the meaning of the nominal voltage and current of the power adaptor (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 adapter, 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 also fluctuate accordingly.

Generally speaking, the true no-load voltage of a common 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. The cost of production is high, so the price is more expensive.

In addition, regarding the nominal current value, no matter 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 One is to cause the output voltage to drop, which is equivalent to internal consumption.

Second, the power supply is the same nominal voltage, the output current is different, can it be used on the same notebook?

The power supply voltage is the same, the output current is different, and it can 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, the current is large depending on the load in the case of the same voltage.

When the notebook is running at high load, the current is larger. When the notebook enters standby mode, the current is smaller, and the power source with large nominal current has sufficient current margin. On the contrary, it is no problem to use the 56w power supply instead of the 72w. The reason is that the power adapter is usually designed with a certain margin, and the load power is less than the power supply. Therefore, this replacement is feasible in general use. But 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 has a base, which comes to a CD-ROM full-speed read disk, plus at the same time Charging the battery is estimated to be dangerous. You should be able to cook your eggs at any time by touching your power supply. Therefore, it is best not to use a small current source instead of a large current source.

Third, the same machine, other people's power supply temperature, my always hot, why?

Don't doubt that your power supply has problems. First, let's see what your notebook is doing. Is it like the two USB hard disks mentioned above, the CPU runs at full speed, the hard disk is crazy to read and write, the optical drive reads the disk at full speed, and the battery is charged at the same time. With music, the screen brightness is the biggest, the wireless network card has been detecting signals, etc. It is very important to make good use of power management and adjust the working status of the books according to the tasks.

Fourth, the power supply nominal voltage is much higher than the voltage of my notebook battery, will not go wrong?

First of all, it is important to know that the power supply to the notebook is different from the power supply to the battery.

Battery powered, the output of the battery is pure DC, very clean, the voltage of the battery is neither possible nor high design. The chemical characteristics of the lithium battery determine that the output voltage of a battery can only be around 3.6V, so Many batteries are connected in a three-stage series, and 10.8V has become a very popular battery voltage. Some batteries have a nominal value slightly larger than an integer multiple of 3.6V, such as 3.7V or 11.2V, etc., in order to protect the battery.

AC/DC Power supply, the situation is more complicated, first need to further voltage regulation and filtering of the added voltage to ensure stable operation under the condition that the power supply performance is not good, the voltage after voltage regulation is divided into two parts of the city, all the way to power the work The other way to charge the battery, the part that supplies the notebook is the same as when the battery is powered, and the part that charges the battery needs to be added to the battery through the charging control circuit of the battery. The control circuit can be complicated, so the power supply The voltage must be greater than the cell voltage to have sufficient capacity to supply to each unit of the charge control circuit. The voltage that is actually added to the cell will never be the nominal voltage of your power supply. Rest assured.