Using portable electronic products, we hope to know the remaining power of the battery and the continuous working time at any time, and adjust relevant applications accordingly. This will undoubtedly be a very convenient thing, especially suitable for business people using smart phones. Battery power detection technology has been common in notebook computers. Most notebook computers have power management options, providing different power supply working modes and battery alarm functions. However, in the more miniaturized portable product market, this technology is still rare.

     The functions provided by portable products are more and more complicated. Users increasingly need to accurately monitor the battery power, so as to flexibly manage the available power supply, clearly display the remaining working time, and extend the system operation time as much as possible. At present, the electricity measurement methods adopted by most mobile phones are relatively simple and lack of accuracy. At present, the mainstream detection method is to simply measure the battery voltage and estimate the corresponding remaining battery capacity. The total power is divided by 4 or 5, that is, the power bar of 4 or 5 grids that can usually be seen on the mobile phone screen. Therefore, the accuracy of each grid is 25% or 20%, which obviously cannot meet the application with high accuracy requirements.

     This voltage estimation method is usually as follows: when a battery is discharged, the voltage of the battery will gradually decrease with the loss of battery power. In this way, a relatively simple and effective corresponding relationship can be obtained, that is, voltage corresponding capacity. According to the discharge curve of the normal use of the battery (such as 100mA discharge), the time is divided into four equal parts. Taking the lithium battery with a charge limit voltage of 4.2V as an example, such a corresponding relationship can be listed as 4.20v-100%, 3.85v-75%, 3.75v-50%, 3.60v-25%, and 3.40v-5% (because the mobile phone cannot completely use up the power of the battery, it may be shut down automatically when it is lower than 3.40v). Obviously, the highest accuracy is only 25%. In addition, the battery voltage will change abruptly with the power emission of RFPA, and will generally decrease by 0.2v-0.3v. If we blindly use the voltage simulation method, the error will be greater. In order to solve the measurement problem that the battery voltage suddenly decreases, the current common method of engineers is to use the software algorithm to filter the average value to average the battery voltage within a period of time. If the average battery voltage in this period of time does decrease, the estimated amount of electricity is indeed reduced. Otherwise, it is considered that the amount of electricity has not changed.

     The method of battery voltage simulating residual power does have some defects, but the method of calculating residual power by real-time monitoring battery consumption with coulometer is very accurate. Fairchild‘s fan4010 is a typical device for this application. It is a current detection sensor, which is specially used to detect the charging / consumption current of the portable device battery. It can convert the current signal through the precision detection resistor into the voltage signal that can be detected by the ADC, so as to calculate the real power consumed in a period of time.

Disclaimer: This article is transferred from other platforms and does not represent the views and positions of this site. If there is infringement or objection, please contact us to del