With the increasing functionality of mobile phones, users' energy requirements for mobile phone batteries are also increasing, and existing lithium-ion batteries have become increasingly difficult to meet consumer demand for normal usage time. In this regard, the industry mainly adopts two methods, one is to develop new battery technologies with higher energy density, such as fuel cells; the other is to work hard on energy conversion efficiency and energy saving of batteries.
Although the technology of providing power for mobile phones has been innovated and developed in recent years, it is far from meeting the needs of the development of mobile phone functions. Therefore, how to improve power management technology and extend battery life has become the main development in mobile phone development and design. One of the challenges.
At the same time, the designer must also understand the consumer's requirements for the mobile phone, which is mainly reflected in the following aspects: First, the small size. This requires increasing the integration of the system, reducing the package size of the components, and reducing the area of ​​the PCB, which may increase the difficulty of solving electromagnetic interference (EMI) in the design. Second, the weight is light. A high-performance battery is required to increase the energy density of the battery in a limited volume and weight. Most mobile phones currently use a single-cell lithium-ion or lithium-polymer battery with a capacity of 850-1000 mAH. Third, the talk time is long. It is required to improve the conversion efficiency of electric energy in the battery during work, reduce the leakage current during standby, and improve the use efficiency. Fourth, the price is cheap. It requires high product integration, low discrete components and low cost. Fifth, the product update is fast. The components are required to be simple and easy to use, easy to design and use, and the hardware and software platforms are unified, which is convenient for adding new functions and features.
Therefore, the power management of the mobile phone should be comprehensively considered in the design of the mobile phone system, balancing the various factors such as power saving, cost, volume and development time, and making the best choice. In general, the overall power management of the mobile phone can be started from the aspects of improving the conversion efficiency of electric energy and improving the efficiency of using electric energy.
First, improve the conversion efficiency of electrical energy
With the ever-increasing demands on power management, the power conversion in handheld devices has gradually moved from the conventional linear power supply to the switching power supply. But not a switching power supply can replace everything, both have their own advantages and disadvantages, suitable for different occasions.
·Linear power supply
LDOs feature low cost, small package size, low peripheral components and low noise. When the output current is small, the cost of the LDO is only a fraction of that of the switching power supply. LDO packages range from SOT23 to SC70, QFN, to WCSP wafer level chip packages, making them ideal for use in handheld devices. For fixed voltage output applications, only 2 to 3 small capacitors are required on the periphery to form the entire solution.
Ultra-low output voltage noise is the biggest advantage of LDO. TI's TPS793285 output voltage ripple is less than 35μVrms and has a very high signal-to-noise rejection ratio, making it ideal for power-supply circuits for noise-sensitive RF and audio circuits. At the same time, in the linear power supply, electromagnetic interference (EMI) caused by large current changes when there is no switch is easy to design.
However, the disadvantage of LDO is its low efficiency and can only be used in the case of buck. The efficiency of the LDO depends on the ratio of the output voltage to the input voltage: η = Vout? Vin. In the case of an input voltage of 3.6V (single-cell lithium battery), the efficiency is 90.9% when the output voltage is 3V, and the efficiency is reduced to 41.7% when the output voltage is 1.5V. Such low efficiency not only wastes a lot of power when the output current is large, but also causes the chip heat to affect the stability of the system.
·Switching power supply
Inductive switching power supplies use inductors as the primary energy storage component to provide continuous current to the load. With a different topology, this power supply can perform buck, boost, and voltage reversal functions.
Inductive switching power supplies have very high conversion efficiencies. The main power loss during product operation includes: conduction loss of built-in or external MOSFET, mainly related to duty cycle and on-resistance of MOSFET; dynamic loss, including switching loss when high-side and low-side MOSFETs are simultaneously turned on And the power loss of driving the MOSFET switching capacitor is mainly related to the input voltage and the switching frequency; the static loss is mainly related to the leakage current inside the IC.
Switching power supply internal structure
These losses are relatively small when the current load is large, so the inductive switching power supply can achieve 95% efficiency. However, when the load is small, these losses become relatively large, affecting efficiency. At this time, the conduction loss and the dynamic loss are generally reduced in two ways. One is the PWM mode: the switching frequency is constant, and the duty ratio is adjusted. The second is the PFM mode: the duty cycle is relatively fixed and the switching frequency is adjusted.
The disadvantage of the inductive switching power supply is that the overall area of ​​the power supply scheme is large (mainly inductance and capacitance), and the ripple of the output voltage is large. Care must be taken when laying out PCBs to avoid electromagnetic interference (EMI).
In order to reduce the need for large inductors and large capacitors and to reduce ripple, it is very effective to increase the switching frequency. TI's TPS62040 has a switching frequency of 1.2MHz. When the output current is 1.2A, the external inductor is only 6.2μH. In the future, TI will also introduce products with higher switching frequency.
·Capacitive switching power supply
The charge pump uses a capacitor as an energy storage component, and its internal switch transistor array controls the charge and discharge of the capacitor. In order to reduce the EMI and voltage ripple caused by the switch, many ICs use a dual charge pump structure. The charge pump also performs the functions of boost, buck, and reverse voltage.
Due to the internal mechanism of the charge pump, when the output voltage is in a certain multiple relationship with the input voltage, such as 2 times or 1.5 times, the highest efficiency can reach more than 90%. However, efficiency will vary with the proportional relationship between the two, and sometimes the efficiency can be as low as 70% or less. Therefore, designers should try to use the best conversion operating conditions of the charge pump.
Due to the limitation of the storage capacitor, the output voltage generally does not exceed 3 times the input voltage, and the output current does not exceed 300 mA. The charge pump characteristics are between the LDO and the inductive switching power supply. They have high efficiency and relatively simple peripheral circuit design. The EMI and ripple characteristics are centered, but there are limits on output voltage and output current.
PanelView Plus 6 Graphic Terminals
Our Bulletin 2711P PanelView™ Plus 6 Graphic Terminals let you monitor, control, and display application status information graphically. These terminals offer the open-platform flexibility of the Windows® CE operating system. They are available in 4-15 in. standard display sizes. FactoryTalk® View Studio Machine Edition software lets you program all of your PanelView Plus 6 graphic terminals.
Features
-
Provides significant improvements over the PanelViewâ„¢ Plus 400 graphic terminals
- Processor speed increased from 350 MHz to 1 GHz
- Screen transition rate is up to 70% faster
- System memory increased from 64MB RAM to 256MB RAM
- Flash storage space increased from 64MB to 512MB
- Includes 80MB nonvolatile storage for applications
- Increased illumination of LED backlight displays
- Greater connectivity to a variety of peripherals such as printers, mice, and keyboards
- Supports ActiveX® Controls
- Integrates with third-party software such as Microsoft® Internet Explorer® and Microsoft Office Viewers
- Supports remote connectivity (VNC and FTP)
- Offers backup restore functionality
- Provides remote recipe and data management through .CSV files
- Uses vector-based graphics from Symbol Factory
- Includes built-in PDF viewer for context-sensitive operator support
- Supports DataStore Plus logging and trending, which eliminates the 300,000 data point limit
PanelView Plus 6 400 Graphic Terminals
- Includes a 4 in. flat-panel color display with 320 x 240 resolution and 18-bit graphics
PanelView Plus 6 600 Graphic Terminals
- Includes a 6 in. flat-panel color display with 320 x 240 resolution and 18-bit graphics
PanelView Plus 6 700 Graphic Terminals
- Includes a 6.5 in. flat-panel color display with 640 x 480 resolution (minimum) and 18-bit graphics
- Supports operator input via keypad (22 funtion keys), via touch screen or via keypad and touch screen
PanelView Plus 6 1000 Graphic Terminals
- Includes a 10.4 in. flat-panel color display with 640 x 480 resolution (minimum) and 18-bit graphics
- Supports operator input via keypad (32 function keys), via touch screen or via keypad and touch screen
PanelView Plus 6 1250 Graphic Terminals
- Includes a 12.1 in. flat-panel color display with 800 x 600 resolution (mimimum) and 18-bit graphics
- Supports operator input via keypad (40 function keys), via touch screen or via keypad and touch screen
PanelView Plus 6 1500 Graphic Terminals
- Includes a 15 in. flat-panel color display with 1024 x 768 resolution (minimm) and 18-bit graphics
- Supports operator input via keypad (40 function keys), via touch screen or via keypad and touch screen
AB PanelView Modules,Terminal Touch Screen,Grayscale Terminal Keypad,Display Module Panel View
Xiamen The Anaswers Trade Co,.LTD , https://www.answersplc.com