The micro usb charger cable is actually a comprehensive transformer composed of a transformer, an AC/DC converter and a corresponding voltage regulator circuit. In short, this comprehensive transformer contains two main components, a transformer and a current converter, and these two The components themselves have power consumption, and their attached voltage regulator circuits are no exception, so the power supply itself is a power consumer.

The energy of the input power supply cannot be 100% converted into the effective energy used by the various components in the host, which is the problem of conversion efficiency we are talking about today.

The conversion efficiency is an important indicator of the micro usb charger cable. High efficiency means that the smaller the loss of the micro usb charger cable itself, the more energy is saved. The conversion efficiency of the micro usb charger cable is the total output power divided by the total input power. Efficiency is defined as: power Efficiency η=Po/Pi. In the formula: Po is the output power, and Pi is the input power.

The relationship between the conversion efficiency and temperature rise of the micro usb charger cable has to be discussed here. Since the corresponding power is lost inside the micro usb charger cable, the conversion efficiency of the micro usb charger cable cannot be 100%, and the power consumed by the power adapter is 100%. In the form of heat generation, the level of heat generated by the power adapter itself mainly depends on the conversion efficiency of the power adapter and the volume of the power adapter. Under certain heat dissipation conditions, the power adapter has a certain temperature rise, that is, the difference between the case temperature and the ambient temperature. The size of the heat dissipation table of the power adapter shell directly affects the temperature rise. The rough estimation of the temperature rise can use the following formula: temperature rise = thermal resistance coefficient × calibration block power consumption. For places with high temperatures, the power adapter needs to be derated It is used to reduce the power consumption of the power adapter, thereby reducing the temperature rise and ensuring that the temperature of the components of the power adapter does not exceed the limit value. In addition to meeting the working requirements of electronic appliances, when the output power of the power adapter is constant, the working temperature rise of the power adapter will affect it. The MTBF has a great influence on the mean time between failures, high efficiency, low temperature rise makes the product long life, and the volume and quality are smaller. When it comes to the volume, we need to talk about the power density.

Most manufacturers of micro usb charger cable use the power density of the product as a standard to measure the effectiveness of the product. The power density is usually expressed by watts/cubic inch: W/in3, if it cannot be used within the specified maximum ambient temperature range The power adapter may not reach the maximum output power of the parameters. The average output power available to the power adapter is the available power density.

The efficiency of the micro usb charger cable used in household appliances is now more and more concerned. If the converter efficiency is low, it means more power consumption. The test of the efficiency of the micro usb charger cable should be measured under the rated input voltage and full load conditions. Few power adapters often work under half load, so we also test light load efficiency when testing, micro usb charger cable designers should pay special attention when choosing topology.