Fan5902 method for extending mobile phone battery usage

　　Author ：Iflowpower – Portable Power Station Supplier

Battery is dead or often charged, which is more worrying? Today, mobile phones (especially smart phones) are rapidly popular all over the world, seven days a week, 24 hours a day, people keep online. Consumers seem to always conduct voice calls, send and receive emails, send text messages and Internet access, never know. However, all of these mobile phone features will consume battery power, between blink, and the battery is only one power.

How can I extend my mobile phone? Of course, theoretically use a larger battery to solve the problem, but the user always wants the phone to be light, and the smoother, the less smooth, so the increase in the battery is unacceptable to the user. Design engineers continue to develop the method of improving power management performance, and focus on three parts of the focus on power consumption. In the mobile phone, in addition to the baseband processor and radio frequency transceiver, three parts that can be consumed by power amplifier (PA), display screen and application / image processor, respectively.

Why will these three part will become a focus? The reason is that people are now talking to and internet. At this time, the display screen is always turned on; in addition, PA must work until the base station transmits voice calls and data; Finally, to watch online movies or other applications, applications The processor must also remain running. The 3G network PA is particularly large when the signal is weak, because it wants more output power to connect to the base station, and keep the linearity requirements to ensure that the 3G signal does not matter.

The power consumption of 3GPa is related to the output power, the larger the output power, the more current in the battery is consumed. When the transmitted signal is more output, consume more current. There are two new technologies that reduce PA power consumption: DC-DC converter and envelope tracking (envelopetracking).

The use of the DC-DC converter in the smart phone is increasing, its working principle is to reduce the power supply voltage of the 3GPa to both the required output power level requirements, and can greatly reduce the level of power consumption. This solution can bring two benefits - the first is to extend the call / usage, the second is reduced heat dissipation. The FAN5902 of the flying semiconductor is a 800mA, 6MHz buck DC-DC converter designed to 3GPa, which can reduce power consumption, extend connection / talk time.

FAN5902 works with baseband processors and 3GPA to reduce power consumption. The baseband processor will set the output power level of the PA according to the information received from the base station, and then convert it to the control voltage of the FAN 5902, and output it to the PA. By dynamically adjusting the power supply voltage and current of PA, FAN5902 can extend at least 15% mobile phone call and data usage time.

The display screen is the second largest power consumption component after PA, because the user is online browsing, reading email or watching mobile TV / Youtube? Video, the display screen is always on state. TFTLCD is currently important display technology, and it is white LED to supply backlight. This trend is more obvious in size LCD display screen market, so it means that there is more white LED to supply a valid backlight to the display screen, which means that it is necessary to supply larger currents for LED and display screen itself.

In high-end mobile phones and intelligent phones, DynamicbacklightControl, DBC and AutoMinousControl, ALC can not only make power consumption as much as possible, but also enhance user visual experience. The ALC should use an ambient light sensor (AmbientlightSensor) to detect the light intensity of the surrounding environment and set the LED current according to the algorithm in the LED driver or application processor. Therefore, the LED current will be set according to lighting conditions.

When the surrounding environment is very dark, the LED current is set to low, while the sun is direct, it is set to the maximum. On the other hand, DBC technology can regulate the LED current according to the image / video content on the display screen: If the content of a scene in the movie is dim, then the LED current is also low; if the scene is brighter,. DBC programs the current according to the pulse width modulation (PWM) signal emitted by the image processor or the LCD driver IC, and changing the displayed movie content.

Figure 3 (a) shows the ALC and DBC operating cases obtained by the flying semiconductor through the screen acquisition software program to showcase ambient light brightness level (left) and corresponding LED current. Although it is not fully explained, the "blue display stick" of the external PWM can still be seen that the static PWM level increases or decreases as the image or movie content. The fan5702 of the flying semiconductor is a 180mA charge pump LED driver with an I2C interface, which can supply ALC and DBC functions via configuration.

The ambient light sensor is connected to the application processor or baseband processor, receives input and determines the appropriate LED current level according to an algorithm of external lighting conditions. This data is sent to the FAN 5702 via the I2C interface, and then set the LED current according to the information. The PWM / EN pin of FAN5702 is programmed for PWM, and is connected to the LCD driver IC.

The latter sends the PWM signal to the FAN 5702 according to the image / video content on the display screen. Figure 4 shows the system module of the FAN5702 of the ALC and DBC simultaneously. Mobile phone display screen uses ALC and DBC to save up to 50% of power consumption.

The third largest power consumption component is an application / image processor; if the display screen is turned on, the chipset will fully run. However, it is not always at full power. For example, when the chipset runs at a lower power level, dynamic voltage adjustment technology (DVS) can be employed.

This is a solution that is very suitable for mobile phones and other portable electronic products because their power supply voltage can be reduced to a lower core voltage and allows the chipset to operate at a lower frequency frequency, thereby helping to reduce power consumption. Here, the sum of the Power (P) and the frequency frequency (f) and the core voltage (V) of the core voltage (V) is proportional. Therefore, the faster the frequency of the processor, the greater the power consumption.

And as the core voltage is reduced, the power consumption is reduced by the square speed. The application processor can be powered by Fan5365. FAN5365 is a 6MHz, 800mA / 1A step DC-DC converter with an I2C interface.

It can supply the best power saving effect. The I2C interface can be used to dynamically program the voltage in the range of 12.5mV to 1.

975V to meet the processing capacity requirements of the chipset. When the user views the video on the web, the FAN 5365 can supply 1.2V core voltage for the application processor to obtain the maximum processing power, and once the movie is completed, the voltage will drop to 0.

8V, enter the lower level working state. There are currently a variety of simple or complex technologies, which can improve the overall power management performance of mobile phones (especially smart phones). By integrated one or all three power management solutions of the PA, display screen and processor core, respectively, can save energy, extend mobile working hours.

These designs are from mobile phone user experience and demand, because users really care about, don't appear on the crust of mobile phones, I don't have to recharge mobile phone without frequent mobile phones.