|LB11961||Single-Phase Full-Wave Fan Motor Driver|
SANYO -> Panasonic
|LB11961 Datasheet PDF : 7 Pages |
Control Timing Chart
(VCC × 28%)
Internal lowest speed setting voltage
f = 25kHz (CP=100pF)
High on duty
(VCC × 30%)
Low on duty
PWM control variable speed mode
(VCC × 16%)
Full speed mode
1. Set minimum speed mode
A VTH voltage level is generated when the thermistor detects the set temperature. At low temperatures, the fan
motor turns at the lowest speed, which is set with the RMI pin. The LB11961 compares the CPWM oscillator
voltage with the RMI pin voltage and sets the duty for the lowest drive state.
2. High speed ↔ low speed mode
The PWM signal is controlled by comparing the CPWM oscillation voltage that cycles between 1.2V and 3. 8V
and the VTH voltage.
When the VTH voltage is lower, the high and low side transistors are turned on, and when the VTH voltage is
higher, the high side transistor is turned off and the coil current is regenerated through the low side transistor.
Thus the output on duty increases as the VTH voltage becomes lower, the coil current increases, and the motor
Rotation speed feedback is provided by the FG output.
3. Full-speed mode
The LB11961 switches to full-speed mode above a certain temperature.
4. Thermistor removed mode
If the thermistor is removed, the VTH input voltage will rise. However, the output will go to full drive at 100%
and the motor will run at full speed.
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