bd6709fs ROHM Co. Ltd., bd6709fs Datasheet - Page 26

• Manufacturer Part Number: bd6709fs
• Description: Dc Brushless Motor Drivers For Cooling Fans Speed Controllable Single-phase Full-wave Dc Brushless Fan Motor Drivers
• Manufacturer: ROHM Co. Ltd.

4) Output Tr simultaneous ON prevention circuit ＜ BD6718FV ＞
＊ BD6721FS 、 BD6722FS
When torque off logic is input by the control signal during fixed time (typ.1ms), the lock protection function becomes off.
It is not influenced at the lock protection time and it is possible to restart at once.
The lock protection function doesn't work in an input frequency that is slower than 1kHz(typ.) when assuming H level
DUTY ≒ 0% of the PWM input signal.
Input signal that frequency are faster than 2kHz.
The capacitor is discharged according to the cycle of hall signal by connecting an external capacitor and resistor to CR
terminal.
When CR terminal voltage is lower than internal reference voltage (2.5V:typ), IC output has a high impedance. High
impedance block in output switching can be changed by changing the capacitance and resistance to be connected to
CR terminal. It allows prevention of simultaneous activation, regardless of switching speed of external Tr.
Hall signal
HALLHYS
ENABLE (INTERNAL IC)
LOCK PROTECTION
A1H
A2H
A1L
A2L
MOTOR OUTPUT
CR
FG
PWM INPUT
H-
H+
Fig.85 PWM signal and lock protection operation ＜ BD6722FS ＞
ON
enable
Discharging time
1ms(typ.)
(T
CR
)
26/40
DELAY
OFF
disable
enable
Hysteresis
ON
2.5V
：High impedance