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53

DP-MB545/537/536 series

IC701 is the motor driver AN44071A.
This motor driver can drive both FB and ADF motors with 1 chip, and can supply up to 1.7A/phase and support up to 2W1-2
phase excitation.
When "CRMEN" signal (IC701_pin40) becomes "H", FB block of motor driver is activated, and motor currents are supplied
from IC701_pin24, pin28, pin29 and pin33 to drive the FB motor coils.
When "ADFMEN" signal (IC701_pin45) becomes "H", ADF block of motor driver is activated, and motor currents are supplied
from IC701_pin1, pin5, pin52 and pin56 to drive the ADF motor coils.

FB motor excitation mode is selected by the logic level of "ST1AB", "ST2AB" and "ST3AB" (IC701_pin35-pin37).
ADF motor excitation mode is selected by the logic level of "ST1CD", "ST2CD" and "ST3CD"(IC701_pin50-pin48).

The relation between motor excitation mode and logic level of "ENABLEAB"/"ENABLECD", "ST1AB"/"ST1CD", "ST2AB"/
"ST2CD" and "ST3AB"/"ST3CD" are shown in below table.

Table1: Motor driver Excitation mode                                               *(pinxx) represents the pin No. of IC701

"DIRAB"(IC701_pin38) and "DIRCD"(IC701_pin47) determine the direction of motor rotation.
Although "DIRCD" determines the Main motor rotation direction, direction is not changed.
So "DIRCD" is fixed "H" level.
The relation between these signals and motor rotation directions are shown in below table.

Table2: Motor rotation direction                                                  *(pinxx) represents the pin No. of IC701

After setting the above signals, clock signal is supplied from IC300_P1 to "CLKAB"(IC701_pin39) and
"CLKCD"(IC701_pin46).
Whenever clock signal is supplied, current value and direction supplied to Scan motors change according to the exci-
tation mode which is determined by above signal levels.
The clock frequency also determines the motor speed.

ENABLEAB(pin40)

or

ENABLECD(pin45)

ST1AB(pin35)

or

ST1CD(pin50)

ST2AB(pin36)

or

ST2CD(pin49)

ST3AB(pin37)

or

ST3CD(pin48)

Excitation 

mode

L

-

-

-

Disable

H

L

L

L

2 Phase(Not 

used)

H

L

H

L

N1-2phase

H

H

L

L

F1-2phase

H

H

H

L

W1-2phase

H

L

L

H

2W1-2phase

Motor

DIRAB(pin38)

Operation Mode

FB

L

Scan

H

Return

Motor

DIRCD(pin47)

Operation Mode

ADF

L

FEED

H

Clutch Release

54

DP-MB545/537/536 series

1. Function

According to the scan speed motor current is controlled for appropriate value.
For example, when scan speed is low, motor has enough driving force.
So to prevent the vibration and noise during motor rotation, motor drive current should be reduced.
When scan speed is high, motor needs much driving force. so much current should be supplied.
In order to control the motor current, VREFAB and VREFCD voltages of IC701 is controlled.
When VREFAB and VREFCD voltages are high, motor currents are increased, and the voltages are low, motor currents are
reduced. 

2. Circuit Diagram

Please refer to the circuit diagram shown in the block diagram of Scanner motor drive circuit (P.52).

3. Circuit explanation

For the sake of VREFAB and VREFCD voltage control, PWM pulse is supplied from IC300_N4.
PWM pulse is integrated by R771, R766, C737, then converted to DC voltage.
This DC voltage is supplied to VREFAB and VREFCD pins of IC701. 
When duty of PWM pulse is high, VREFAB and VREFCD voltages are increased and when duty is low, 
VREFAB and VREFCD voltages are decreased.

4. Timing chart of current control

Following timing charts are the example of VREFCD voltage corresponding to PWM pulse duty.

55

DP-MB545/537/536 series

1. Function

If motor driver can supply more than 15 watts, FB motors may become fire hazards.
To prevent the risk of fire, this circuit is provided.
 

2. Circuit diagram

3. Circuit explanation

When the current supplied from 24V exceeds 0.44A, the voltage between two registers R764 and R767 becomes more than
0.6V (=0.44Ax2.7ohm/2), consequently both Q709 and Q708 turn on, then "STBY" signal (IC701_pin44) becomes "Low"
level.
When "STBY" signal becomes "Low" level, IC701 is deactivated and currents of both motors are cut off.
So the currents which IC701 can supply are limited to less than 0.44A and the wattage is also limited to less than 10.7W
(=0.44Ax24V).
By limiting the wattage less than 15W, risk of fire hazard is eliminated.

Also "CRM1"signal is provided from IC300_P2 to base of Q708.
This signal is designed to become "High" when software can not control motors properly by some accidents.
When base of Q708 becomes "High", "STBY" signal becomes "Low" and motor currents are cut off.
Therefore even in the case of software can not control motors, motors stop automatically for securing safety.

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DP-MB545/537/536 series

Correspondent table of operation