| With the development of the society and the continuous improvement of people's quality of life, People's requirements of all kinds of portable electronic communication products, which develop from the first large heavy "mobile phone " or the one restricted by the on-board battery to the intelligent multi-media mobile phone now, are becoming more and more diversified. Science and technology is changing rapidly every day, now the phone not only owns a fine shape, but also tends to hold more functions, such as a digital camera (DSC), music player (MP3) and the Global Positioning System (GPS), and so on. In order to achieve such a rich variety of features, many of the components are needed, most of which have different voltage and current, therefore, the design of the power supply module, which is the core of all the smartphone parts.Based on the basic principle of mobile phone, this article focused on the design and its ideas of the smartphone's power module circuit. From the phone's power supply process and internal components to start, not only considered the working principle and process, but also make a detailed description of the best option principles and the best option for the components and the power management chips. In addition, the common problems that happen to the smart phone for use in the actual process are analyzed in this article, and both their reasonable causes and ruled out methods are pointed out too. In order to expound more clearly, according to the contents above, this article mainly include the following several parts:1. The Power Management Module ComparisonThe mobile power management module can use the following two programmes, one is the discrete power management devices and the other is the power management unit PMU which is integrated, and each of the two has its own advantages. Although there are some shortcomings with the PMU, such as large footprint, a little troublesome Layout and design, yet it can be used to reduce costs, simplify customer supply chains, prevent the products being replaced, and many other advantages, therefore,it has become the trends of power management technology of portable devices such as mobile phone. Nevertheless, the discrete power management devices still own living space, the market of the high-performance discrete power management chip is still bullish, and especially the high-performance LDO and white LED driver chips, some of their advantages can not be replaced by the PMU in a short period of time.2. Power Management Chip OoptionsThis article introduces not only the circuit and the performance analysis of the power supply, but also the voltage changes in the battery voltage detection process. If the power supply management chip can be power saving, high-performance and multi-functional and occupy a small area of the circuit board, it is possible to make mobile phones smaller and work for more hours; it has been widely used at present. And most of them contain a complete lithium rechargeable electric circuit based on the CMOS technology.3. The Power Supply Module DesignThis section is divided into five main modules: the process of machine switching, the process of charging, the process of the battery voltage detection, back-up power supply circuit, as well as the clamshell process of clamshell phones. Furthermore, the charging process can be divided into four stages, namely pre-charge, current fixed charge, voltage fixed charge and trickle charge, combined with circuit schematic of the battery charging process, and makes a specific analysis and description of the work process with the different signals input.Before designing the power supply modular, in order to facilitate the design and description, at first, this article expounds the three basic concepts that related to the power supply circuit which is PMU (Power Management Unit), DPM (Dynamic Power Management), LDO (Low Dropout Linear Regulator), and introduces the work process of the mobile phone. Then, analyzing from the battery power supply, the boot signal, the voltage boost circuit, the non-controlled power output and the controled power output, totally five parts, to the internal components of the cell phone power supply, based on the results of which, the power module design can have a good start. However, in fact, power, cost, volume, development time and other factors should also be considered generally, and then make the best choose. Generally speaking, the overall management mechanisms of the power supply can be confirmed considering increasing the mobile phone's energy conversion efficiency and the energy efficiency in use.4. The Smartphone System's Power ManagementAccording to the up-to-date trends of mobile phone technology, the power suppply management can be divided into chip power management, camera flash power management, boost backlight power management, W-CDMARF power management, battery power management and low drop-out linear regulator management.Chip power management need to take two points into account, one is the DC-DC step-down switching voltage regulator of the mobile processor power supply, its dynamic voltage range is less than 1.5V in the work mode or less than 1.8V in the sleeping mode. The other is that its tolerance is tight, its load current is high, its transient response is steep, and it has intelligent peripheral management interface, also the most important thing is that the converters need to work in multi-mode configuration in order to maintain the high light load efficiency, and reduce the interfere of RF noise; Camera flash power management needs to consider the light output and lighting patterns requirements of a phone with a million pixels, it can be generated through adding current bias to the white LED compulsively or adding smaller current bias to many LEDs, the camera flash drive circuits based on LED can be based on LED configuration, as well as a variety of performance step-down induction of a compromise pressor, or step-up charge pump converter; As for the boost backlight power management, to obtain uniform brightness and to avoid the leakage current in the shutdown mode, as well as to adjust brightness to match the optimal efficiency of lighting conditions is very important, the designers can use smaller magnetic components to meet the requirements of low if working at the high-frequency PWM / PFM.; However, as for the low dropout linear regulator, the typical cell phone uses the 7-12 low dropout linear regulators to supply power for a variety of low-power sub-system, and most of them are integrated into the general power management Unit (PMU) .5. Smartphone's Common Faults MaintenanceThe common fault of cell phone's power supply, the TCL mobile phone is taken as an example in this article in order to carry out the corresponding analysis.First of all, analyze all parts of the circuit features, including charging circuits, motor circuits, audio circuits, flip monitor circuit, LCD backlight drive circuit, as well as key background light circuit, introduce the corresponding functional circuit Work and performance characteristics according to their own circuit schematic, and describe the specific components of the circuit functions.Then, the common faults analysis mainly focused on the causes and measures to rule out. The common faults are devided into two categories: One is relatively simple, which can be solved rosin joint inspection and replacing basically, such as handset doesn't sound, the screen doesn't show, or no backlight, and so on; The other is the relatively more complicated and needs to be analyzed and resolved in detailed, which mainly includes such failures as death, there is no or sometimes not send/receive signals, not boot, touch-screen invalid / positioning inaccurately or the problems of signals and network and so on.We can get a better understanding of the role that the mobile power supply module plays, with the awareness of the common faults that may happen to the power supply, and get away from the error areas when designing, eventually make mobile phones work more effectively and faster. |
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