NJM3777 New Japan Radio, NJM3777 Datasheet - Page 6

• Manufacturer Part Number: NJM3777
• Description: DUAL STEPPER MOTOR DRIVER
• Manufacturer: New Japan Radio

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
current of approximately 500 mA. R
absolute maximum output current which is 900 mA. Chopping frequency, winding inductance and supply voltage
also affect the current, but to much less extent.
tolerance and low temperature coefficient.
M,peak
For accurate current regulation, the sensing resistor should be a 0.5 - 1.0 W precision resistor, i. e. less than 1%
APPLICATIONS INFORMATION
= 0.1•V
R
/ R
S
[A]
Figure 6. Typical stepper motor driver application with NJM3777
Figure 7. Typical microstepping application with NJU39612
To
+2.5V
P
+5 V
+5 V
GND (V
GND
(V
V
CC
CC
13
14
16
20
12 k
4 700 pF
)
(+5 V)
6
5
1
10
11
15
14
17
D0
D7
A0
WR
CS
RESET
V
CC
S
8
Ref
. The peak current through the sensing resistor (and the motor winding) can be
12
)
NJU39612E2
Phase
Dis
V
Phase
Dis
V
RC
R1
R2
S
0.1 F
1
2
should be selected for maximum motor current. Be sure not to exceed the
6,
18, 19
GND
V
V DD
1
SS
2
4
17
V
7,
CC
13
NJM3777E3
C
Sign
Sign
DA
1
9
DA
1
1
2
2
0.47
V
3
18
2
19
R S
MM1
+5 V
5
3
E
12 k‰
1
4700 pF
15
14
17
10
11
8
16
12
Phase
Dis
V
Phase
Dis
V
RC
C
R1
R2
V
0.1 F
2
1
2
6,
18, 19
MM2
GND
1
2
20
0.47
V
7,
CC
NJM3777E3
13
R S
C
S
M
M
M
M
22
1
, a 2.5 V reference voltage will produce an output
9
E
A1
B1
A2
B2
0.47 ‰
2
V
0.1 F
MM1
5
3
E
4
2
21
23
1
R S
16
C
V
2
MM2
Pin numbers refer
to EMP package.
20
0.47 ‰
GND (V
+
10 F
M
M
M
M
22
STEPPER
E
A1
B1
A2
B2
MOTOR
2
0.1 F
R S
V
4
2
21
23
MM
MM
Pin numbers refer
to EMP package.
)
GND (V
+
10 F
STEPPER
MOTOR
V
MM
MM
)
NJM3777