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<Stop operation>
In order to stop the motor rotation, following 2 signals are supplied from IC300.
1. SS signal (Output pin: Pin B12/Output Signal: "L")
When this signal is inverted by transistor Q502 and becomes "H", motor recognize this signal as "stop" signal.
2. Brake signal (Output pin: Pin C12/Output Signal: "L")
When this signal is inverted by transistor Q526 and becomes "H", motor recognize this signal as "brake on" signal.

Timing Chart of Stop operation

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General

Scanner motor drive circuit is consist of motor current control circuit ,FB (Flat Bed) motor driver and ADF (Auto Document Feeder:
equipped model only) motor driver .

1. Circuit explanation

According to the scan speed, each motor current is controlled for appropriate value.
When scan speed is low, motor current is reduced to prevent the vibration during motor rotation. 
When scan speed is high, motor needs much driving force. so much current should be supplied.

For the control of motor current, Vref voltage of each motor driver is controlled.
When Vref voltage is high, motor current is increased, and the voltage is low, motor current is reduced.
In order to control Vref voltage, PWM pulse is supplied from IC300 pin D8 .
PWM pulse is inverted by Q521 and integrated by R533, R534, and C567, then convert to DC voltage.

This DC voltage is supplied to Vref pin of each motor driver through Q522.
When duty of PWM pulse is high, Vref voltage is decreased and when duty is low, Vref voltage is increased.

For FB motor, motor current is controlled approx. 0.1A-0.25A.
For ADF motor, motor current is controlled approx. 0.2A-0.35A (ADF epuipped model only).

2. Circuit diagram

3. Timing chart

Following timing charts are the example when PWM pulse duty are approx 9% and 45%.

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1. Functions

This motor functions for main operations including FB copy and PC scan.
This motor feeds CIS unit with synchronizing for reading.

2. Motor operation

During motor driving, pin A8 of IC 300 become low level, then motor driver IC502 is activated.
Stepping pulses are output from IC300 pins A9, B9, C9,A10, B10, and C10, causing driver IC502 pin 3, 7, 9 and 13 to drive
the motor coil.
A 1-step rotation of this motor feeds 0.021mm of CIS unit.

3. Circuit Diagram

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1. Timing chart

2. Wave form