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A monolithic low-voltage H-bridge brushless DC (BLDC) vibration motor driver with an integrated high sensitivity Hall sensor has been presented in 0.18 μm high-voltage complementary metal-oxide semiconductor technology. To improve the motor start-up reliability, a full-on start mode is applied to realise a high-speed start sequence by shortening the start-up time. Meanwhile, an active start function is activated to prevent dead point phenomenon if the motor magnet pole sensed by the built-in Hall sensor does not change during the motor starting. This complete one-chip solution for driving the BLDC vibration motors provides significantly enhanced reliabilities, including thermal shutdown and under voltage lockout protection functions, and fully eliminates the need for any external components. The measured results show that the motor driver chip has a typical operating point of 2 mT and a typical releasing point of - 2 mT, showing a hysteresis magnetic property of 4 mT. The chip is very robust. It can operate well within a low supply voltage range of 2-4 V and can output a maximum of 300 mA peak current while the ambient temperature ranges from - 40 to 85°C.
Date of Publication: July 2013