njw4351 New Japan Radio Co.,Ltd, njw4351 Datasheet - Page 13

• Manufacturer Part Number: njw4351
• Description: Unipolar Stepper Motor Driver
• Manufacturer: New Japan Radio Co.,Ltd

PRECAUTIONS
1. Never disconnect the device or PC-board when power is supplied.
2. Remember that excessive voltages might be generated by motor, even though clamping diodes are used.
3. Choose a motor that is proportional to the current you need to establish desired torque. A high supply voltage
4. Avoid VMM and VDD power supplies with serial diodes (without filter capacitor) and common ground with
5. To change actual motor rotation direction, exchange motor connections at OUT1A and OUT1B (OUT2A and
6. Half-stepping
7. Drive Circuits
8. Phase Turn-off Considerations
8.1. Precautions against high voltage using the Zener-diode turn-off circuit
8.1.1. When VP is a positive voltage: VMM > VZ + Vd
8.1.2 When VP is a negative voltage: VMM < VZ + Vd
the configuration of the turn-off circuit or the kickback voltage generated in it. In this condition there is a danger
of a malfunction occurring in the logic circuit inside the device.
the diodes connected in series with the Zener-diode is Vd, the voltage VP of the phase output (OUT1A,
OUT1B, OUT2A, OUT2B) terminal when the turn-off operation have occurred is expressed by the following
equation. VP = VMM – (Vz + Vd)
speed operation of the stepper motor. Note, however, that depending on the Zener voltage, VZ, the voltage
potential at the phase output terminal may become negative, so design the turn-off circuit as indicated below.
will gain better stepping performance. If the motor is not specified for the VMM voltage, a current limiting
resistor will be necessary to connect in series with center tap. This changes the L/R time constant.
VDD.
OUT2B).
half-step mode, motor resonances are reduced. In a two-phase motor, the electrical phase shift between the
windings is 90 degrees. The torque developed is the vector sum of two windings energized. Therefore, when
only one winding is energized, which is the case in half-step mode for every second step, the torque of the
motor is reduced by approximately 30%. This causes a torque ripple.
and quickly turned off when not in use.
properly suppressed. Refer to the turn-off circuits described in Figures 11 to 14.
to insert diodes in series with the phase output terminals.
In the half-step mode, the power input to the motor alternates between one or two phase windings. In
The voltage potential at the phase output terminal may sometimes become negative (GND or below) due to
Refer the Zener-diode turn-off circuit (see Fig.15). Zener-diode voltage value is Vz and the forward voltage of
The higher voltage, Vz, used, the shorter is the turn-off time of the winding current, thus producing high
High-performance stepper motor operation requires windings to be energized immediately at phase turn-on
The circuit configuration is that of Fig.16. In order to prevent a malfunction due to a negative voltage, be sure
When the winding current is turned off, induced high voltage spike will damage the drive circuits if not
The circuit configuration is that of Fig.15.
Set the Zener voltage. For example, if VMM is 12 V, VZ + Vd is no higher than12V.
NJW4351
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