NJM3775

s APPLICATIONS INFORMATION

Current control

The regulated output current level to the motor winding is determined by the voltage at the reference input and the

value of the sensing resistor, R

expressed as:

I

With a recommended value of 0.5 ohm for the sensing resistor R

2.5 V reference voltage will produce an output

current of approximately 500 mA. R

absolute maximum output current which is 850 mA. Chopping frequency, winding inductance and supply voltage

also affect the current, but to much less extent.

For accurate current regulation,

the sensing resistor should be a 0.5 -1.0 W precision resistor, i. e. less than 1% tolerance and low temperature -

coefficient.

Figure 7. Half stepping system where NJM3517 is used as controller circuit in

order to generate the necessary sequence to the NJM3775.

NJM

3517

HSM

GND

3

2

4

11

10

7

6

16

9

8

fl

fl

P

P

DIR

STEP

INH

Half/Full

Step

Direction

Step

V

CC

+

V

(+5 V)

GND (V

)

B

A

A1

B1

4.7

µF

CC

CC

4 x

10 k

Ω

12 k

Ω

4 700 pF

Phase

Dis

V

Phase

Dis

V

1

1

2

2

R1

R2

E

C

E

C

GND

RC

NJM3775

M

M

M

M

A1

B1

A2

B2

V

CC

VV

MM1

MM2

3

1

20

22

9

10

7

12

4

19

11

5,

6,

17, 18

215

21

8

11

2

2

R S

R S

14

13

16

STEPPER

MOTOR

V

MM

Pin numbers refer

to DIP package.

+

10

µF

GND (V

)

0.1

µF

MM

1.0

Ω

1.0

Ω

0.1

µ F

Figure 6. Typical stepper motor driver application with NJM3775.

Phase

Dis

V

Phase

Dis

V

1

1

2

2

R1

R2

E

C

E

C

GND

RC

NJM3775

12 k

Ω

4 700 pF

0.47

Ω

0.47

Ω

M

M

M

M

A1

B1

A2

B2

V

CC

VV

MM1

MM2

+5 V

+5 V

3

1

20

22

9

10

7

12

4

19

11

5,

6,

17, 18

215

21

8

11

2

2

R S

R S

14

13

16

STEPPER

MOTOR

V

MM

Pin numbers refer

to DIP package.

+

10

µF

0.1

µF

GND (V

)

GND (V

)

0.1

µF

MM

CC