EUM6804 ds6804 ver0.1 apr. 2011 1 pwm fan motor driver with slope control and low duty startup description EUM6804 is a fan motor driver for brushless dc fan motor. it integrates three types speed control mode s, low duty startup function, soft switched output, lo ck protection, hall bias, fg output, shutdown mode, quick restart and tsd. with these modes and functio ns, EUM6804 can not only be applied to dc fans which require different speed curves, but also be applied to nb and other portable equipments which require silence and low power dissipation. the three types speed control modes are pwm control mode, vcc control mode with slope adjustable, normal vcc control mode. low duty startup function makes it possible for dc fan to start and restart u nder a very low pwm duty cycle. soft switched output drive s dc fan in low noise and low vibration. if a dc fan is stalled by the external force or obstacles, overdri ve current may incur coil overheat and burning. to prevent motor from overheating, the lock protection circuit shuts down the internal power devices for a few seconds after the motor lock is detected. then the auto restart circuit resumes to power up the internal po wer devices. EUM6804 has built in hall ic bias output, motor rotation speed feedback (fg). with its shutdo wn mode and quick restart, EUM6804 consume little power dissipation during shutdown time and can be started at once regardless of lock detection time. features single-phase full-wave driver system three speed control mode pwm control mode vcc control mode with slope adjustable normal vcc control mode low duty startup sd = h: enable low duty startup sd = l: disable low duty startup soft switched drive for silent application lock detection and automatic restart shutdown mode and quick restart low standby current (pwm = l) fg output hall bias output thermal shutdown protection available in udfn-10 package rohs compliant and 100% lead (pb)-free halogen-free applications nb cooling fan silent fan motor application circuit figure 1. pwm control mode
EUM6804 ds6804 ver0.1 apr. 2011 2 application circuit (continued) figure 2. vcc control mode with slope adjustable figure 3. normal vcc control mode
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