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NJM3774 の電気的特性と機能

NJM3774のメーカーはNew Japan Radioです、この部品の機能は「DUAL STEPPER MOTOR DRIVER」です。


製品の詳細 ( Datasheet PDF )

部品番号 NJM3774
部品説明 DUAL STEPPER MOTOR DRIVER
メーカ New Japan Radio
ロゴ New Japan Radio ロゴ 




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NJM3774 Datasheet, NJM3774 PDF,ピン配置, 機能
NJM3774
DUAL STEPPER MOTOR DRIVER
s GENERAL DESCRIPTION
The NJM3774 is a switch-mode (chopper), constant-
current driver with two channels: one for each winding of a
two-phase stepper motor. The NJM3774 is equipped with a
TTL level compatible Disable input to simplify half-stepping
operation. The circuit is well suited for microstepping
applications together with the matching dual DAC
NJU39610. In full/half stepping applications, the NJM3517
can be used as a phase generator (translator) to derive the
necessary signals for the NJM3774. The NJM3774 con-
tains a clock oscillator, which is common for both driver
channels, a set of comparators and flip-flops implementing
the switching control, and two output H-bridges. Voltage
supply requirements are +5 V for logic and +10 to +45 V for
the motor. Maximum output current is 1000mA per channel.
s PACKAGE OUTLINE
NJM3774D2 NJM3774FM2
s FEATURES
• Dual chopper driver
• 1000 mA continuous output current per channel
• Specially matched to the Dual DAC NJU39610
• Packages DIP22 / PLCC28
s BLOCK DIAGRAM
NJM3774
Phase 1
Dis1 VR1
C1
VCC
V
CC
+
E1
RQ
S
Logic
+
RC
Logic
+ SQ
R
Figure 1. Block diagram
Phase 2
Dis 2 VR2
C2
GND
E2
M A1
M B1
VMM1
VMM2
M B2
M A2

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NJM3774 pdf, ピン配列
NJM3774
s FUNCTIONAL DESCRIPTION
Each channel of the NJM3774 consists of the following sections: an output H-bridge with four transistors, capable
of driving up to 1000mA continuous current to the motor winding; a logic section that controls the output transistors;
an S-R flip-flop; and a comparator. The clock-oscillator is common to both channels.
Constant current control is achieved by switching the output current to the windings. This is done by sensing the
peak current through the winding via a resistor, RS, effectively connected in series with the motor winding during the
turn-on period. As the current increases, a voltage develops across the resistor, and is fed back to the comparator.
At the predetermined level defined by the voltage at the reference input VR, the comparator resets the flip-flop,
turning off the output transistors. The current decreases until the clock oscillator triggers the flip-flop, turning on the
output transistors, and the cycle is repeated.
The current paths during turn-on, turn-off and phase shift are shown in figure 3. Note that the upper recirculation
diodes are connected to the circuit externally.
External recirculation diodes
1 VMM
2
3
Motor Current
RS
12
3
Fast Current Decay
Slow Current Decay
Time
Figure 3. Output stage with current paths
during turn-on, turn-off and phase shift.


3Pages


NJM3774 電子部品, 半導体
NJM3774
s APPLICATIONS INFORMATION
Current control
The output current to the motor is de-termined by the voltage at the reference input and value of sensing resistor,
RS.
Chopping frequency, winding induc-tance and supply voltage also affect the current, but to much less extent. The
output current can be switched off com-pletely by a HIGH input level at the Dis-able input (Dis1 and Dis2 for
respective channels). When Disable goes HIGH, all four transistors in the output stage are switched off, and the
output current rapidly drops to zero (“fast current decay” – see figure 3).
The peak motor current through the sensing resistor and the motor winding can be expressed as:
IM,peak = 0.18 • ( VR / RS ) [A]
A 2.5 V reference voltage and a 0.47 ohm sensing resistor will produce an out-put current level of approximately
960 mA.
To improve noise immunity at the VR input, the voltage control range can be increased to 5 V if RS is corre-
spondingly changed (for example to 1ohm for 900 mA max output current).
External components
For the device to function properly, four external free-wheeling diodes must be connected, as in figure 6. The
diodes should be of fast type with a reverse recovery time of less than 100 ns. Com-monly used types are UF4001
or BYV27.
A low pass filter in series with the com-parator input prevents erroneous switch-ing 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 in-troduces 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 what is defined by the
comparator threshold, VCH , set by the reference input VR (VCH = 450 mV at VR= 2.5 V).
The time constant of the low-pass fil-ter may therefore be reduced to minimize the delay and optimize low-current
performance. Increasing the time constant may result in unstable switching. The time constant should be adjusted
by changing the C value.
C
+5 V
V MM
+
0.1 µF
22 11 5
D1 D2
10 µF
19
V CC
Phase1
V MM1
V MM2 MA1
18 Dis1
20 VR1
26 Phase 2
27 Dis2
25 V R2
RC GND
NJM3774
C1 E1 C2
MB1
MA2
MB2
E2
23 1, 2, 21 10 24
6
+5 V 15 k
3, 9,
1 k
1 k
13, 14,
3300 pF
15, 16,
17, 28.
820 pF
RS
820 pF
RS
12
8
4
7
GND (VCC )
0.68
0.68
STEPPER
MOTOR
D3 D4 V MM
D1 - D4 are UF 4001 or
BYV 27, trr 100 ns.
Pin numbers refer to
PLCC package.
Figure 6. Typical stepper motor driver application with NJM3774.

6 Page



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共有リンク

Link :


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