We launched with a single-phase H- bridge PWM control "220V Cooling Fan" motor driver chip --AM4961. The chip is the use of variable speed PWM control of single-phase brushless DC fan motor drive circuit, in addition to direct by changing the voltage VTH to the governor, but also an external thermistor to control the fan speed when the system temperature is high, "220V Cooling Fan" fast speed, low temperature, slow speed, to meet the system cooling requirements while saving system power, reduce system noise, mainly used in the CPU of "220V Cooling Fan" on, to meet PC, workstation, telecommunications and LAN servers, and industrial control and instrumentation system cooling requirements.