EUM6811 Datasheet, PDF (1/1 Pages) Eutech Microelectronics Inc – 3-Phase Sensorless BLDC Fan Motor Driver

Preliminary
EUM6811
3-Phase Sensorless BLDC Fan Motor Driver
DESCRIPTION
EUM6811 is a 3-phase sensorless BLDC fan motor
driver. It senses the Back Electromotive Force of the
motor in rotation and provides corresponding
commutation current to the motor. The use of
sensorless technology means no Hall sensors are
needed. The absence of the Hall sensor makes the
fabrication of the motor easier and is especially
suitable for ultra-small motors.
EUM6811 integrates PWM speed control, soft
switching, lock protection, auto restart, fan tachometer,
under voltage lock out circuit and forward/reverse
functions.
As applying 3-phase driver method, PWM mode
controls fan speed by adjusting duty cycle of PWM
signal. Internal soft switching function drives fan
motor in low noise and low vibration ways. EUM6811
can drive motor from stop mode to rotation mode by
adjusting the external capacitor between OSC pin and
VSS pin. If a motor is stalled by external force or
obstacles, over drive 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 power devices. If the lock still persists,
EUM6811 shuts down power devices for another few
seconds. The lock protection time is built-in and does
not need external components. During rotation, FG
outputs motor speed feedback signal. The motor
rotation direction can be changed by setting FR to high
or low.
Application Circuit
FEATURES
3-Phase Sensorless Drive
(No Hall Sensor Needed)
Input Voltage Range:1.8V~6.0V
Total Driver H+L R_ON less than 950mΩ
UVLO Protection
PWM Speed Control and Soft Switching
Few External Components
20µA Low Standby Current
Built in TSD
UDFN Small Package with Thermal Pad
(3mm×3mm×0.5mm for Small Fan)
RoHS Compliant and 100% Lead (Pb)-Free
Halogen-Free
APPLICATIONS
NB Fan, Low Noise Fan and Low Power
Consumption Fan
DS6811 Ver0.1 Mar. 2013
Figure 1.
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