JRC NJM3770AE2, NJM3770AD3, NJM3770AFM2 Datasheet

STEPPER MOTOR DRIVER

■ GENERAL DESCRIPTION ■ PACKAGE OUTLINE

NJM3770A is a stepper motor driver, which consists of a
LS-TTL compatible logic input stage, a current sensor, a
monostable multivibrator and a high power H-bridge output
stage. The NJM3770A is a high power version and pin­compatible with the NJM3717.Two NJM3770A and a small
number of external components form a complete control
and drive unit stepper motor systems.

NJM3770AD3

■ EATURES

NJM3770A

NJM3770AE2

• Half-step and full-step operation

• Switched mode bipolar constant current drive

• Wide range of current control 5 -1800 mA

• Wide voltage range 10 - 45 V

• Thermal overload protection

• Packages DIP16 (Batwing) / PLCC28 / EMP20

■ BLOCK DIAGRAM

V

CC

Schmitt

& &&&

+
–

+
–

+
–

Current Sensor

Trigger

Phase

GND

I

1

I

0

V

R

C

Time
Delay

1

Monostable
t = 0.69 • R • C

off

T

NJM3770AFM2

V

≥1

≥1

T T

E

MM

Output Stage

V

MM

NJM3770A

≥1

≥1

M

A

M

B

Figure 1. Block diagram

■ PIN CONFIGURATIONS

M

1

B

2

T

3

V

MM

4

GND

5

GND

GND
GND

V

CC

Phase

6
7
8

I

9

1

10

NJM

3770AE2

Figure 2. Pin configurations

NJM3770A

E

20
19

M

A

18

V

MM

17

GND

GND

16
15

GND

14

GND

V

13

R

C

12
11

I

0

M

V

MM

GND
GND

V

CC

I

Phase

1

B

T

2
3

NJM

4

3770AD3

5
6
7

1

8

16
15
14
13
12
11
10

9

E
M

A

V

MM

GND
GND
V

R

C
I

0

N/C

N/C

GND

MM

V

GND

GND

GND

GND

N/C

1

GND

282726

GND

GND

N/C

25

N/C

24

V

R

23

C

22

N/C

21

I

0

Phase

20

I

19

1

CC

V

432

5
6

M

A

7

E

8
9

10

M

B

T

11

NJM

3770AFM2

12131415161718

MM

V

GND

GND

■ PIN DESCRIPTION

EMP DIP PLCC Symbol Description

1110MBMotor output B, Motor current flows from MA to MB when Phase is high.
2 2 11 T Clock oscillator. Timing pin connect a 56 kΩ resistor and a 820 pF in

parallel between T and Ground.

3 3,14 12,4 V

MM

4-7, 4,5, 1-3,9, GND Ground and negative supply. Note these pins are used for heatsinking.
14-18 12,13 13-17,28 Make sure that all ground pins are soldered onto a suitable large copper

8618V

CC

9719I1Logic input. It controls, together with the I0 input, the current level in the output

10 8 20 Phase Controls the direction of the motor current of M

11 9 21 I

0

12 10 23 C Comparator input. This input senses the instantaneous voltage across the

13 11 24 V

19 15 6 M

R

A

20 16 8 E Common emitter. Connect the Sense resistor between this pin and ground.

Motor supply voltage, 10 to 40 V. Pin 3(12) and pin 14(4) should be wired to
gether.

ground plane for efficient heat sinking.
Logic voltage supply normally +5 V.

stage.
The controllable levels are fixed to 100, 60, 20, 0%.

and MB outputs.

A

Motor current flows from M

to MB when the phase input is high.

A

Logic input. It controls, together with the I1 input, the current level in the output
stage.

The controllable levels are fixed to 100, 60, 20, 0%.

sensing resistor, filtered through a RC Network.
Reference voltage. Controls the threshold voltage of the comparator and hence
the output current. Input resistance: typically 6.8 kΩ ± 20%.
Motor output A, Motor current flows from MA to MB when Phase is high.

NJM3770A

■ FUNCTIONAL DESCRIPTION

The NJM3770A is intended to drive a bipolar constant current through one winding of a 2-phase stepper motor.

Current control is achieved through switched-mode regulation, see figure 3 and 4.

Three different current levels and zero current can be selected by the input logic.

The circuit contains the following functional blocks:

• Input logic

• Current sense

• Single-pulse generator

• Output stage

Input logic
Phase input

The phase input determines the direction of the current in the motor winding. High input forces the current from
terminal MA to MB and low input from terminal MB to MA. A Schmitt trigger provides noise immunity and a delay
circuit eliminates the risk of cross conduction in the output stage during a phase shift.

Half- and full-step operation is possible.

External recirculation
diodes

2

1

3

R

S

Motor Current

1 2

Fast Current Decay
Slow Current Decay

3

Time

Figure 3. Output stage with current paths
for fast and slow current decay.

200 mA/div 1 ms/div

0

100µs/div

Figure 4. Motor current (IM ),
Vertical : 200 mA/div,
Horizontal: 1 ms/div,
expanded part 100 µs/div.