The AH9479/80/81 is a single chip solution for driving single coil brushless DC motors. It combines a motor driver with a high sensitivity Hall sensor, which simplifies the PCB design and makes the fabrication of small-size motors possible. The AH9480 has an open-drain tachometer output FG that follows the Hall sensor latching output. The AH9481 has an open-drain rotation detection output RD that is active low when the motor is spinning and goes high when blocked. When there is no motion about 0.4 second, the IC will automatically detect the locked rotor conditions, and enter protection mode, shutting off the motor driver for 4 seconds. Then, the IC will turn on the motor driver for 0.4 second to detect whether there is rotation condition, if fails, the IC will shut off motor driver for four seconds again. This sequence will be repeated until rotation condition is detected, and the IC enters normal operation. This feature can effectively prevent the IC from overheating and damage due to long-time locked rotor condition. "Soft-switch" is used to reduce the vibration and acoustic noise. Thermal-shutdown protection ensures that the motor driver operates under specified temperature ranges.