NJM3773 데이터 시트보기 (PDF) - Japan Radio Corporation
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NJM3773 Datasheet PDF : 9 Pages
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NJM3773
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, RS. The peak current through the sensing resistor (and the motor winding) can be
expressed as:
IM,peak = VR / RS
[A]
With a recommended value of 0.5 ohm for the sensing resistor R , a 0.25 V reference voltage will produce an output
S
current of approximately 500 mA. RS should be selected for maximum motor current. Be should not to exceed the
absolute maximum output current which is 850 mA. Chopping frequency, winding inductance and supply voltage
also affect the current, but to much less extent.
To improve noise immunity on the comparator inputs (VR and C), the control range may be increased to 0.5 V if RS
is correspondingly changed to 1 ohm for a maximum output current of 500 mA.
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.
+5 V
VCC
0.1 µF
0.1 µF
V MM
+
10 µF
12
4
19
V
9 Phase 1 CC
V
MM1
V
MM2
MA1
3
10 Dis1
7 VR1
14
Phase 2
13 Dis2
16
V R2
RC GND
NJM3773
C1
E1 C2
MB1 1
20
MA2
MB2 22
E2
11 5, 6,
8
2 15
21
+5 V 12 kΩ
17, 18
STEPPER
MOTOR
4 700 pF
GND (VCC )
RS
0.47 Ω
RS
0.47 Ω
Pin numbers refer
to DIP package.
GND (VMM )
Figure 6. Typical stepper motor driver application with NJM3773.
+5 V V CC
V MM
+
4.7 µF
0.1 µF
0.1 µF
+
10 µF
Micro-
controller
D/A
82 kΩ
D/A
82 kΩ
10 kΩ
GND (VCC )
10 kΩ
1000
pF
12
4
19
V
9 Phase 1 CC
V
MM1
V
MM2
MA1
3
10 Dis1
7 VR1
14
Phase 2
13 Dis2
16 V R2
RC GND
NJM3773
C1
E1 C2
MB1 1
20
MA2
MB2 22
E2
11 5, 6, 8
2 15
21
20 kΩ
17, 18
1 kΩ
1 kΩ
STEPPER
MOTOR
1000
pF
2 700 pF
820 pF
RS
0.68 Ω
820 pF
RS
0.68 Ω
Pin numbers refer
to DIP package.
GND (VMM )
Figure 7. Microstepping system where a microcontroller including DACs provides
analog current control voltages as well as digital signals to the NJM3773.
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