【作者】 刘占军；

【导师】 白天蕊；

【作者基本信息】 西南交通大学 ， 电路与系统， 2013， 硕士

【摘要】 针对笔记本散热风扇的应用需求,本文基于UMC0.6μm BiCMOS工艺,研究设计了一款单相低噪声直流风扇驱动电路。首先对单相无刷直流电机的工作原理进行了分析,将反映电机转速、转子相位等信息的霍尔信号,经过电路内部采用不对称结构的功率运算放大器的300倍线性放大,处理转化为功率管的控制信号,实现对电机的持续驱动。软开关驱动使得当输入的霍尔信号幅值较小时,输出的驱动信号是缓慢变化的,而当输入的霍尔信号幅值较大时,输出的驱动信号是快速变化的。除完成对电机的基本控制功能外,对电机进行了两个方面的保护设计,即锁死检测和自动重启功能：当外力或障碍物等原因导致电机锁定不转时,锁死检测电路能自动关断电机的驱动电流5秒,以防止电机因为过热而烧毁。同时每隔5秒对电机进行一次0.5秒左右的尝试重启,以便恢复电机能够正常转动；过温保护功能：当温度高于176℃时关断电路,当温度降到152℃以下时重新开启,使电路恢复正常工作。在电路整体设计中,根据功能要求把电路划分为带隙基准源、滞回比较器、过温保护、锁死检测及自动重启和输出驱动等功能模块；根据整体的设计指标,对部分模块完成晶体管级的电路设计,并对整体电路的参数进行了仿真和分析；同时对BiCMOS工艺及其版图设计规则作了简单介绍。最后通过对芯片测试分析,所有参数均达到了设计指标。内置功率MOS晶体管的导通电阻为1.2Ω,具备较强的带负载能力。同时输入电压范围为2.2V～6V时,电源电压与风扇转速基本呈线性关系,具有较宽的转速调节范围和低噪声。更多还原

【Abstract】 To meet the demands of notebook cooling fan, this paper is about the design and study on a single-phase low-noise DC fan driver IC based on the UMC’s0.6μm BiCMOS process.Firstly, the working principle of the single-phase brushless DC motor was analyzed. The input of HALL signal that reflects the motor speed and rotor phase was linearly amplified by300times through the internal asymmetric structure of the power operational amplifier, thus converting into a control signal of the power tube to realize continuous driver for motor. Soft switched drive mode makes the output signal gentle when the amplitude of HALL signal is small, oppositely, it makes the output signal steep when the amplitude of HALL signal is big. In addition to the basic control functions of motor, it is designed with two protection circuit. If the motor is stalled by external force or obstacles, overdrive current may incur coil overheat/burning. To prevent this, lock detection circuit can shut down the driver for5seconds after motor lockup. Then automatic restart circuit will try to power up the driver for500mS every5seconds. The thermal protection circuit shut down the chip at176℃, and restart it at152℃.According to the functional requirements, the chip is divided into different function module, such as bandgap reference, hysteresis comparator, over-temperature protection, lock detection and automatic restart, and output driver. Following the overall design of indicators, it is designed at transistor level of several modules and the parameters of the whole circuit is simulated and analyzed. In the meantime, it does provide a brief introduction to the BiCMOS process and the design rules of layout.Finally, according to the test of this chip, majority of the electrical characteristics are according with the design indicators. Moreover, the power MOSFET’s on-resistance is just12Ω, so it has a huge load capacity. The test results shows that there is a linear relationship between the power supply voltage and the fan speed in the range from2.2V to6V of input voltage, so the speed of cooling fan could be adjusted in a wide range and low noise is obtained.更多还原