Research On Key Module Of Voice - Coil Motor Driver

With the development of the camera phone to the high-pixel direction, it’s began to focus feature request. In general, customers want a higher pixel camera phone with auto-focus function. However, in the traditional way, the focus function will greatly increase the board size and thickness of the phone. To solve this problem, the voice coil motor is applied in camera phones. Due to the increasing demand for voice coil motor applied in smartphones, terminal shipments and high-quality camera modules gradually, the advanced functions and higher performance has become an important research issue.In most auto fouse applications, lens are drived by voice coil motor driver. The location of the lens in camera module is proportional to the size of drived current. When the current of voice coil motor changes to the default value, the lens may overshoot and ringing in the final position. The settling time of ringing extends the lapse time. In order to reduce the settling time and, this project is used programmable output current of slew rate control arithmetic to eliminate the ringing. When program a new current, the device will gradually track initial and final desired step between each step. The delay time between these levels are programmable.Combined with the needs of customers, this project is addressed the existing voice coil motor driver chip applications limitations and weaknesses of power, compled the analysis, design of the system architecture and the module circuit design, from hardware implementation to test verification. In the system design and circuit design stage, the following innovations are the slope of the advanced control algorithms, a novel bandgap reference circuit and a practical design for testability.This chip is implemented using CSMC0.5μm CMOS standard process, the operating voltage is2.3V to5.5V, and the chip area is1.42mm2. The measurement results show that in I2C fast mode, the driver chip to meet the design requirements. At the same time, the chip is capable of peak output current102mA to meet the application requirements.