NJM3771FM2 [NJRC]
DUAL STEPPER MOTOR DRIVER; 双步进电机驱动器
| 型号： | NJM3771FM2 |
| 厂家： | 
NEW JAPAN RADIO |
| 描述： | DUAL STEPPER MOTOR DRIVER |
| 文件： | 总9页 (文件大小：173K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
NJM3771
DUAL STEPPER MOTOR DRIVER
■ GENERAL DESCRIPTION
■ PACKAGE OUTLINE
The NJM3771 is a stepper motor driver, which circuit is
especially developed for use in microstepping applications in
conjunction with the matching dual DAC (Digital-to-Analog
Converter) NJU39610.
The NJM3771 contains a clock oscillator, which is common
for both driver channels; a set of comparators and flip-flops
imple menting the switching control; and two H-bridges with
internal recirculation diodes. Voltage supply requirements are
+5 V for logic and +10 to +45 V for the motor. Maximum
output current is 650 mA per channel.
NJM3771E3
NJM3771D2
■ FEATURES
NJM3771FM2
• Dual chopper driver
• 650 mA output current per channel
• Selectable slow/fast current decay for improved high-
speed microstepping
• Specially matched to Dual DAC NJU39610
• Packages DIP22 / EMP24(Batwing) / PLCC28
■ BLOCK DIAGRAM
E
Phase
CD
V
C
1
1
1
1
R1
NJM 3771
–
+
V
V
CC
Q
CC
R
S
M
M
A1
B1
+
–
Logic
V
MM1
MM2
+
V
–
M
M
B2
A2
–
+
Logic
RC
S
R
Q
+
–
E
Phase
CD
V
C
GND
2
2
2
2
R2
Figure 1. Block diagram
NJM3771
■ PIN CONFIGURATIONS
M
1
2
22
21
20
19
M
E
B1
B2
E
NC
1
2
1
2
3
4
5
NC
MB2
E2
24
23
MB1
E1
V
3
V
MM2
MM1
22
21
20
M
4
M
A2
A1
V
5
6
25
24
V
C
MA2
MM2
R2
MA1
VMM1
GND
E
2
VMM2
GND
2
GND
GND
5
18 GND
17 GND
16 Phase
NJM
3771E3
M
M
7
23 RC
B2
B1
6
7
19
18
NJM
3771D2
6
8
22
21
20
V
CC
GND
Phase1
CD1
GND
NJM 3771FM2
GND
9
C
V
17
16
15
14
13
1
8
9
Phase2
CD2
Phase
CD
7
1
2
E
1
10
11
R1
8
15 CD
2
V
19 CD
1
1
MM1
VR1
C1
10
11
VR2
C2
V
9
14
13
V
R2
R1
VCC 12
RC
10
11
C
C
1
2
V
CC
12 RC
Figure 2. Pin configurations
■ PIN DESCRIPTION
Refer to Figure 2
EMP
2
3
DIP
1
2
PLCC
8
10
Symbol
MB1
E1
Description
Motor output B, channel 1. Motor current flows from MA1 to MB1 when Phase1 is HIGH.
Common emitter, channel 1. This pin connects to a sensing resistor to ground.
Motor supply voltage, channel 1, 10 to 40 V. VMM1 and VMM2 should be connected together.
Motor output A, channel 1. Motor current flows from MA1 to MB1 when Phase1 is HIGH.
4
3
11
VMM1
MA1
5
4
12
6,7,
5,6,
1-3,9,
GND Ground and negative supply. Note: these pins are used thermally for heat-sinking.
Make sure that all ground pins are soldered onto a suitably large copper ground
plane for efficient heat sinking.
18,19 17,18 13-17,28
8
7
8
18
19
20
21
Phase1 Controls the direction of motor current at outputs MA1 and MB1. Motor current flows from MA1
to MB1 when Phase1 is HIGH.
9
CD1
VR1
C1
Current decay control, channel 1. A logic HIGH on this input results in slow current decay,
a LOW results in fast current decay, see “Functional Description.”
Reference voltage, channel 1. Controls the threshold voltage for the comparator and hence
the output current. Input resistance is typically 2.5 kohms, ±20%.
Comparator input channel 1. This input senses the instantaneous voltage across the
sensing resistor, filtered by an RC network. The threshold voltage for the comparator is
(0.450 / 2.5) • VR1, i.e. 450 mV at VR1 = 2.5 V.
10
11
9
10
12
13
11
12
22
23
VCC
RC
Logic voltage supply, nominally +5 V.
Clock oscillator RC pin. Connect a 15 kohm resistor to VCC and a 3300 pF capacitor to
ground to obtain the nominal switching frequency of 26.5 kHz.
14
13
24
C2
Comparator input channel 2. This input senses the instantaneous voltage across the
sensing resistor, filtered by an RC network. The threshold voltage for the comparator is
(0.450 / 2.5) • VR1, i.e. 450 mV at VR1 = 2.5 V.
15
16
17
14
15
16
25
26
27
VR2
Reference voltage, channel 2. Controls the threshold voltage for the comparator and hence
the output current. Input resistance is typically 2.5 kohms, ±20%.
Current decay control, channel 2. A logic HIGH on this input results in slow current decay,
a LOW results in fast current decay, see “Functional Description.”
CD2
Phase2 Controls the direction of motor current at outputs MA2 and MB2. Motor current flows from MA2
to MB2 when Phase2 is HIGH.
20
21
22
23
19
20
21
22
4
5
6
7
MA2
VMM2
E2
Motor output A, channel 2. Motor current flows from MA2 to MB2 when Phase2 is HIGH.
Motor supply voltage, channel 2, 10 to 40 V. VMM1 and VMM2 should be connected together.
Common emitter, channel 2. This pin connects to a sensing resistor to ground.
Motor output B, channel 2. Motor current flows from MA2 to MB2 when Phase2 is HIGH.
MB2
NJM3771
■ FUNCTIONAL DESCRIPTION
Each channel of the NJM3771 consists of the following sections: an H-bridge output stage, capable of driving up
to 650 mA continuous motor current (or 500 mA, both channels driven), a logic section that controls the output
transistors, an S-R flip-flop, and two comparators. The oscillator is common to both channels.
Constant current control is achieved by switching the current to the windings. This is done by sensing the (peak)
voltage across a current-sensing resistor, RS, effectively connected in series with the motor winding, and feeding
that voltage back to a comparator. When the motor current reaches a threshold level, determined by the voltage at
the reference input, VR, the comparator resets the flip-flop, which turns off the output transistors. The current
decreases until the clock oscillator triggers the flip-flop, which turns on the output transistors again, and the cycle is
repeated.
The current-decay rate during the turn-off portion of the switching cycle, can be selected fast or slow by the CD
input.
In slow current-decay mode, only one of the lower transistors in the H-bridge (those closest to the negative
supply) is switched on and off, while one of the upper transistors is held constantly on. During turn-off, the current
recirculates through the upper transistor (which one depends on current direction) and the corresponding free-
wheeling diode connected to VMM, see figure 3.
In fast current decay mode, both the upper and lower transistors are switched. During the off-time, the freewheel-
ing current is opposed by the supply voltage, causing a rapid discharge of energy in the winding.
Fast current decay may be required in half- and microstepping applications when rapid changes of motor current
are necessary. Slow current decay, however, gives less current ripple, and should always be selected, if possible,
to minimize core losses and switching noise.
2
1
3
R
s
Motor Current
2
3
1
Time
FAST Current Decay
SLOW Current Decay
Figure 3. Output stage with current paths
during turn -on, turn-off and phase shift
NJM3771
■ ABSOLUTE MAXIMUM RATINGS
Parameter
Pin no. (DIP)
Symbol
Min
Max
Unit
Voltage
Logic supply
Motor supply
Logic inputs
Comparator inputs
Reference inputs
11
3, 20
7, 8, 15, 16
10, 13
VCC
VMM
VI
VC
VR
0
0
-0.3
-0.3
-0.3
7
45
6
VCC
7.5
V
V
V
V
V
9, 14
Current
Motor output current
Logic inputs
Analog inputs
1, 4, 19, 22
7, 8, 15, 16
10, 13
IM
II
IA
-700
-10
-10
-
+700
-
-
mA
mA
mA
mA
Oscillator charging current
12
IRC
5
Temperature
Operating junction temperature
Storage temperature**
TJ
TS
-40
-55
+150
+150
°C
°C
** Circuit only. The packaging can handle max 60°C
■ RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
VCC
VMM
IM
TJ
tr
Min
4.75
10
-650
-20
-
Typ
Max
5.25
40
650
+125
2
Unit
V
V
mA
°C
µs
Logic supply voltage
Motor supply voltage
Motor output current ***
Junction temperature ****
Rise time logic inputs
Fall time logic inputs
Oscillator timing resistor
5
-
-
-
-
tf
RT
-
2
-
15
2
20
µs
kohm
*** In microstepping mode, “sine/cosine” drive where I1 = 650 • cos(q) and I2 = 650 • sin(q) mA, otherwise 500 mA/channel both
channels fully on.
****See operating temperature chapter.
E
2
Phase
CD
8
V
9
C
1
1
1
1
R1
10
7
NJM 3771
| V
– V
|
MA
MB
t
–
+
V
V
I
CC
CC
Q
CC
R
S
11
M
M
4
A1
B1
+
–
Logic
t
off
1
on
50 %
V
3
MM1
MM2
15 kΩ
+
I
MM
V
20
R
–
T
M
M
22
19
B2
A2
–
+
I
I
OL
t
M
Logic
I
RC
RC
12
V
E
S
R
Q
t
+
–
d
V
3
300 pF
CH
V
CC
C
T
5, 6, 17, 18
GND
21
E
16 15 14
CD
13
C
Phase
V
R2
2
2
2
2
I
I
I
I
IH
IL
A
I
I
C
I
A
1
kΩ
V
V
V
I
IH
V
R
t
V
V
V
M
MM
V
C
E
CH
A
IL
V
V
MA
V
C
R
820 pF
t
1
+ t
on
+
f =
D =
R
C
C
s
S
t
t
t
on
off
on
off
Figure 4. Definitions of symbols
Figure 5. Definition of terms
NJM3771
■ ELECTRICAL CHARACTERISTICS
Electrical characteristics over recommended operating conditions, unless otherwise noted. -20°C < TJ < +125°C
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
General
Supply current
Total power dissipation
ICC
PD
-
38
1.4
50
1.6
mA
W
VMM = 40 V, IM1= 450 mA, IM2= 0 mA.
Notes 2, 3.
V
MM = 40 V, IM1 = IM2 = 318 mA.
1.6
1.0
1.8
1.5
W
Notes 2, 3.
Ta = +25°C, dVC/dt ≥ 50 mV/µs.
Note 3.
Turn-off delay
td
-
µs
Logic Inputs
Logic HIGH input voltage
Logic LOW input voltage
Logic HIGH input current
Logic LOW input current
VIH
VIL
IIH
2.0
-
-
-
-
-
-
-
0.6
20
-
V
V
µA
mA
VI = 2.4 V
VI = 0.4 V
IIL
-0.4
Reference Inputs
Input resistance
Input current
RR
IR
VTO
Ta = +25°C
Ta = +25°C, VR = 2.5 V.
-
5
0.5
29
-
kohm
mA
mV
1.0
38
Turn-off voltage
20
Comparator Inputs
Threshold voltage
| VCH1 - VCH2 | mismatch
Input current
VCH
VCH,diff
IC
RC = 1 kohms, VR = 2.5 V
RC = 1 kohms
430
-
-10
450
1
-
470
-
1
mV
mV
µA
Motor Outputs
Lower transistor saturation voltage
Lower transistor leakage current
Lower diode forward voltage drop
Upper transistor saturation voltage
Upper transistor leakage current
Upper diode forward voltage drop
IM = 500 mA
VMM = 41 V, VE = VR = 0 V, VC = VCC
IM = 500 mA
-
-
-
-
-
-
1.00
-
1.10
1.20
-
1.20
300
1.25
1.35
300
V
µA
V
V
µA
V
IM = 500 mA
VMM = 41 V, VE = VR = 0 V, VC = VCC
IM = 500 mA
1.00
1.25
Chopper Oscillator
Chopping frequency
fs
CT = 3300 pF, RT = 15 kohms
25.0
26.5
28.0
kHz
■ THERMAL CHARACTERISTICS
Parameter
Symbol
Conditions
Min
Typ
11
40
9
35
13
Max
Unit
°C/W
°C/W
°C/W
°C/W
°C/W
Thermal resistance
RthJ-GND DIP package.
RthJ-A DIP package. Note 2.
RthJ-GND PLCC package.
-
-
-
-
-
-
-
-
-
-
RthJ-A
PLCC package. Note 2.
RthJ-GND EMP package.
RthJ-A
EMP package. Note 2.
-
42
-
°C/W
Notes
1. All voltages are with respect to ground. Currents are positive into, negative out of specified terminal.
2. All ground pins soldered onto a 20 cm2 PCB copper area with free air convection.
3. Not covered by final test program.
4. Switching duty cycle D = 30%, fS = 26.5 kHz
NJM3771
■ APPLICATIONS INFORMATION
Current control
The output current to the motor winding is mainly determined by the voltage at the reference input and the value of
the sensing resistor, RS.
Chopping frequency, winding inductance, and supply voltage will affect the current level, but to much less extent.
Fast current decay setting will produce somewhat lower (average) current than slow current decay. The peak
current through the sensing resistor (and motor winding) can be expressed as:
IM,peak = 0.18 • (VR / RS) [A]
i.e., with a recommended value of 1 ohm for the sensing resistor, RS, a 2.5 V reference voltage will produce an
output current of approximately 450 mA. To improve noise immunity on the VR input, the control range may be
increased to
5 volts if RS is correspondingly changed to 2 ohms.
V
V
(+5 V)
CC
MM
+
0.1 µF
0.1 µF
10 µF
11
3
20
V
V
V
4
CC
MM1
MM2
M
M
M
7
A1
Phase
1
8
9
CD
1
1
B1
A2
B2
V
R1
NJM 3771
19
16
Phase
2
15
14
CD
2
22
M
V
R2
GND
C
E
C
E
2
RC
12
STEPPER
MOTOR
2
1
1
2
21
13
5, 6,
17, 18
10
1 kΩ
1 kΩ
15 kΩ
+5 V
Pin numbers refer
to DIP package.
820 pF
1.0 Ω
820 pF
1.0 Ω
3 300 pF
R
R
S
S
GND
(V
)
GND (V
)
MM
CC
Figure 6. Typical stepper motor application with NJM3771
V
V
(+5 V)
CC
MM
+
0.1 µF
0.1 µF
10 µF
11
3
20
5
14
V
V
V
MM2
4
V
CC
MM1
M
M
M
D0
D7
DD
7
8
9
A1
3
4
2
Phase
Sign
1
1
CD
1
CD
1
1
7
B1
A2
B2
V
DA
To
P
R1
1
NJM3771
NJU39610
19
15
16
A0
A1
16
20
19
21
Phase
Sign
2
2
6
17
22
1
15
14
WR
CS
CD
2
CD
2
22
M
V
DA
RESET
R2
2
+2.5V
V
V
GND
C
E
C
E
2
RC
12
Ref
STEPPER
MOTOR
SS
18
2
1
1
2
21
13
5, 6,
17, 18
10
1 kΩ
1 kΩ
15 kΩ
+5 V
Pin numbers refer
to DIP package.
820 pF
1.0 Ω
820 pF
1.0 Ω
3 300 pF
R
R
S
S
GND
(V
)
GND (V
)
MM
CC
Figure 7. Microstepping system with NJU39610 and NJM3771
NJM3771
External components
The voltage across the sensing resistor is fed back to the comparator via a low-pass filter section, to prevent
erroneous switching due to switching transients. The recommended filter component values, 1 kohm and 820 pF,
are suitable for a wide range of motors and operational conditions.
Since the low-pass filtering action introduces a small delay of the signal to the comparator, peak voltage across
the sensing resistor, and hence the peak motor current, will reach a slightly higher level than the threshold, VC, set
by the reference voltage
(VC = 450 mV @VR = 2.5 V).
The time constant of the low-pass filter may therefore be reduced to minimize the delay and optimize low-current
performance, especially if a low (12 V) supply voltage is used. Increasing the time constant may result in unstable
switching.
The frequency of the clock oscillator is set by the R-C combination at pin RC. The recommended values give a
nominal frequency of 26.5 kHz. A lower frequency will result in higher current ripple and may cause audible noise
from the motor, while increasing the frequency results in higher switching losses and possibly increased iron losses
in the motor.
The sensing resistor, RS, should be selected for maximum motor current. The relationship between peak motor
current, reference voltage and the value of RS is described under “Current control” above. Be sure not to exceed
the maximum output current which is 650 mA per channel (or 500 mA per channel, both channels fully on, see
“Recommended Operating Conditions”).
Motor selection
The NJM3771 is designed for bipolar motors, i.e., motors that have only one winding per phase. A unipolar motor,
having windings with a center tap, can also be used, see figure 8.
The chopping principle in the
NJM3771 is based on a constant frequency and a varying duty cycle. This
scheme imposes certain restrictions on motor selection. Unstable chopping can occur if the chopping duty cycle
exceeds approximately 50%. To avoid this, it is necessary to choose a motor with a low winding resistance. Low
winding resistance means less inductance and will therefore enable higher stepping rates, however it also means
less torque capability. A compromise has to be made.
Choose a motor with the lowest possible winding resistance that still gives the required torque and use as high
supply voltage as possible without exceeding the maximum recommended 40 V. Check that the chopping duty
cycle does not exceed 50% at maximum current.
Since the NJM3771 produces a regulated, constant output current it is not necessary to use a motor that is rated
at the same voltage as the actual supply voltage. Only rated current needs to be considered. Typical motors to be
used together with the NJM3771 have voltage ratings of 5 to 12 V, while the supply voltage usually ranges from 24
to 40 V.
Best for high speed
Best for high torque
NJM3771
NJM3771
Figure 8. Connection of unipolar motors
NJM3771
General
Phase inputs
A logic HIGH on a Phase input gives positive current flowing out from MA into MB. A logic LOW gives a current in
the opposite direction.
Slow/fast current decay
A logic HIGH on the CD input gives slow current decay, a logic LOW gives fast current decay.
Heat sinking
Soldering the four center pins onto a free PCB copper area of 20 cm2 (approx. 1.8" x 1.8", copper foil thickness =
35 µm) permits the circuit to operate with a maximum of 320 mA output current, both channels driving, at ambient
temperatures up to +70°C. Consult figures 9 and 14 in order to determine the necessary copper area for heat
sinking if higher currents are required.
Thermal shutdown
The circuit is equipped with a thermal shutdown function that reduces the output current at chip temperatures
above +160°C.
Thermal resistance [°C/W]
80
70
22-pin
60
DIP
50
24-pin EMP
40
30
28-pin
PLCC
20
5
10
15
20
25
30
35
PCB copper foil area [cm2]
PLCC package
DIP package
Figure 9. Thermal Resistance vs. PC Board copper area and suggested layout
NJM3771
■ TYPICAL CHARACTERISTICS
V
d
(V)
VCE Sat (V)
Vd (V)
°C
T = 25
j
°C
T = 25
j
1.0
.8
.6
.4
.2
0
1.2
1.0
1.0
.8
°C
T = 125
°C
T = 25
j
j
°C
T = 125
j
.8
.6
.4
.2
.6
°C
T = 125
j
.4
.2
0
0
0
.10
.20
.30
.40
.50
.60
0
.10
.20
.30
.40
.50
.60
.10
.20
.30
.40
.50
.60
IM (A)
IM (A)
IM (A)
Figure 10. Typical upper diode
Figure 11. Typical source saturation
Figure 12. Typical lower diode
voltage drop vs. recirculating current voltage vs. output current
voltage drop vs. recirculating current
VCE Sat (V)
PD (W)
1.0
.8
°C
T = 25
j
3.0
2.0
1.0
VMM = 36V
VMM = 14V
°C
T = 125
j
.6
.4
.2
0
0
0
.10
.20
.30
.40
.50
.60
.10
.20
.30
.40
.50
.60
IM (A)
IM (A)
Max allow power is
Figure 13 Typical sink saturation
voltage vs. output current
Figure 14. Power dissipation vs. motor current,
both channels driven, Ta = 25°C
The specifications on this databook are only
given for information , without any guarantee
as regards either mistakes or omissions.
The application circuits in this databook are
described only to show representative
usages of the product and not intended for
the guarantee or permission of any right
including the industrial rights.
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