Application of Power IC in Mobile Phones

Mobile phones are the most important application for power management ICs. Multimedia and 3G mobile phones have increasing demands for high-definition video, multimedia data streams, audio playback, clearer displays, and more entertainment, but these functions consume a lot of power, and most of them have different power supply voltages. As the current demand continues to increase, they require more power. For example, when upgrading from 2G voice phones to 3G video phones, the power demand doubles. Integrating more diverse functions into the same mobile phone will increase its power consumption, which is a clear trend in the development of power management chips in the future.

The advantage of DC/DC conversion is that it is applicable to both step-up and step-down, and has high efficiency. Currently, there are power management solutions using automatic PFM/PWM and DC/DC+LDO dual modes. Although the cost of either solution will be higher than that of LDO, it can indeed solve the problem of LDO being inefficient and only being able to be used for step-down. In the future, the increase in the production of 3G mobile phones and the improvement of mobile phone power management functions will stimulate the development of the mobile phone power management IC market to a certain extent.

Since mobile phones use LDO to power various parts of mobile phones, although LDO has the characteristics of low cost, small package, few peripheral devices and low noise, its conversion efficiency is low and can only be used for voltage reduction. In addition, the efficiency of LDO depends on the ratio of output/input voltage. When the input voltage is 3.6V and the output voltage is 1.5V, the efficiency is only 41.7%. Such low efficiency will not only waste a lot of power when the output current is large, but also cause the chip to heat up and affect the stability of the system. The various components of 3G mobile phones need to be powered by multiple voltage levels. In many cases, especially when the voltage difference is large, LDO can no longer meet the power supply requirements. Therefore, the DC/DC solution has become a solution to replace LDO.