am4961 BCD Semiconductor Manufacturing Limited, am4961 Datasheet - Page 11

• Manufacturer Part Number: am4961
• Description: Ingle Phase Full Wave Direct Pwm Motor Driver
• Manufacturer: BCD Semiconductor Manufacturing Limited

Operating Diagram
Note 6:
1. Low Speed Setting Mode
When VPWM voltage is higher than VMIN pin voltage,
motor speed is settable by VMIN pin voltage. The mini-
mum drive duty cycle is settable by comparing COSC
oscillating voltage and VMIN pin voltage.
VPWM voltage is decided by variation of PWM duty.
2. Variable Speed Setting Mode
When VPWM voltage is lower than VMIN pin voltage,
PWM control system works by comparing VPWM voltage
and COSC voltage. If VPWM voltage is higher, the ON
duty cycle of the upper side transistors will be minimized
and motor speed becomes lower. Vice versa.
3. Full Speed Rotation Mode
Jun. 2008 Rev. 2. 2
SINGLE PHASE FULL WAVE DIRECT PWM MOTOR DRIVER
VMIN Voltage
Lowest speed setting voltage
0V
COSC Output
FG Output
V
CC
VPWM adjustable Voltage
Low Speed
Figure 10. Operating Diagram of AM4961 (Note 6 )
f
OSC
=25kHz (C
OSC
=100pF)
11
At a certain PWN duty, when VPWM voltage is lower than
the low side of COSC output voltage, the motor will run at
full speed.
PWM Variable
BCD Semiconductor Manufacturing Limited
High Speed
Data Sheet
AM4961
V
V
osc
osc