bd6761fs ROHM Co. Ltd., bd6761fs Datasheet - Page 18

• Manufacturer Part Number: bd6761fs
• Description: Motor Driver Ic Series For Printers Three-phase Brushless Motor Pre-driver For Paper Feed Us
• Manufacturer: ROHM Co. Ltd.

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High-side gate
Low-side gate
Short brake (BD6761FS and BD6762FV)
Forward/reverse rotation circuit (BD6761FS and BD6762FV)
Start/stop circuit (BD6762FV)
Low voltage protection circuit (BD6761FS and BD6762FV)
Built-in 120° slope PWM logic (BD6762FV)
BD6761FS operates the short brake action with the ACC and DEC pins set to low, while BD6762FV does so with the SB pin set to
OPEN or high. At the time of short brake, the high-side gate is turned off and the low-side is turned on. At the time of short brake
operating, the current flows to the output FET, which is set by the motor's counter electromotive voltage and coil impedance. Since
this current does not flows through the overcurrent protection (current limit) detection resistor, the overcurrent protection does not
operate as the IC operates. Therefore, the current must not exceed the output FET rating.
Forward /reverse rotation of motor can be switched according to the FR pin input conditions. Logics of the hall input and output
conditions according to the FR pin input conditions are shown in the I/O conditions table (P.12/24). If the FR pin is switched during the
motor rotation, when the prevention circuit in the IC operates, the feed through current does not flow. However, since the motor
current flows toward the power source due to the electromotive force, the voltage may be raised if the power source does not have
the power supply voltage absorption ability. Examine the capacitor characteristics between the power supply and ground sufficiently.
Power supply voltage and step-up voltage must not exceed the absolute maximum ratings. When the physical measures are taken,
such as increasing the capacitor value which is connected between the power supply and ground, characteristics must be monitored
prior to use.
When the ST/SP pin is in the sate of OPEN or high, IC is on standby. In standby mode, some circuit operations are turned off to
reduce the current consumption.
When the ST/SP pin is in the state of low, the IC operates.
An IC with a built-in low voltage protection circuit. When VCC becomes lower than 11.5 V (Typ.), the high-side and low-side gates are
both turned off and turn the coil off. Protection off voltage is 12.0 V (Typ.) and hysteresis width is 0.5 V (Typ.).
Since the motor locking protection detection circuit operates in BD6762FV during the low voltage protection operation, if the low
voltage protection operating time becomes longer than the motor locking protection detection time, the operation moves to the motor
locking protection operation after the low voltage protection operation.
It is possible to perform 120° drive by setting 120/SL pin to OPEN or making high. 120° slope drive is possible by setting the 120/SL
pin to OPEN or making high. Low noise design is realized by reducing the electromagnetic sound generated at the time of phase
switching by means of gradually changing the output PWM on-duty during 120° slope energization. However, at the time of startup or
the hall input frequency is lower than about 3 Hz (Typ. value), it becomes 120° drive. When the hall input frequency is more than
about 3 Hz (Typ. value) and the rise of hall U-phase is detected 7 times, it switches to the 120° slope drive.
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Fig.18 High/Low-side Simultaneous On Prevention Timing Chart
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18/24
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