njm13775 New Japan Radio Co.,Ltd, njm13775 Datasheet - Page 8

• Manufacturer Part Number: njm13775
• Description: Dual Stepper Motor Driver
• Manufacturer: New Japan Radio Co.,Ltd

NJM13775
Phase inputs
opposite direction. A time delay prevents cross conduction in the H-bridge when changing the Phase input.
Dis (Disable) inputs
decreasing output current to zero.
VR (Reference) inputs
to an adequate level. The divider consists of closely matched resistors. Nominal input reference voltage is 5V.
Interference
circuitry. To reduce potential interference there are a few basic rules to follow:
Motor selection
imposes certain restrictions on motor selection. Unstable chopping can occur if the chopping duty cycle exceeds
approximately 50 %. See figure 5 for definitions. To avoid this, it is necessary to choose a motor with a low winding
resistance and inductance, i.e. windings with a few turns.
to be considered. Typical motors to be used together with the NJM13775 have a voltage rating of 1 to 6 V, while the
supply voltage usually ranges from 12 to 40 V.
same torque capability at low speed, the reduced number of turns in the winding in the low resistive, low inductive motor
must be compensated by a higher current. A compromise has to be made. Choose a motor with the lowest possible
winding resistance and inductance, 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.
Thermal shutdown
above 160°C. Normal operation is resumed when the temperature has decreased.
Programming
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A logic HIGH on a Phase input gives a current flowing from pin M
A logic HIGH on the Dis inputs will turn off all four transistors of the output H-bridge, which results in a rapidly
The Vref inputs of the NJM13775 have a voltage divider with a ratio of 1 to 10 to reduce the external reference voltage
Due to the switching operation of NJM13775, noise and transients are generated and might be coupled into adjacent
● Use separate ground leads for power ground (the ground connection of R
● Decouple the supply voltages close to the NJM13775 circuit. Use a ceramic capacitor in parallel with an electrolytic
● Do not place sensitive circuits close to the driver. Avoid physical current loops, and place the driver close to both the
The NJM13775 is designed for two-phase bipolar stepper motors, i.e. motors that have only one winding per phase.
The chopping principle of the NJM3775 is based on a constant frequency and a varying duty cycle. This scheme
It is not possible to use a motor that is rated for the same voltage as the actual supply voltage. Only rated current needs
Low inductance, especially in combination with a high supply voltage, enables high stepping rates. However, to give the
The circuit is equipped with a thermal shutdown function that turns the outputs off at a chip (junction) temperature
Figure 8 shows the different input and output sequences for full-step, half-step and modified half-step operations.
ground of external analog and digital circuitry. The grounds should be connected together close to the GND pins of
NJM13775.
type for both V
motor and the power supply connector. The motor leads could preferably be twisted or shielded.
CC
and V
MM
. Route the power supply lines close together.
A
into pin M
S
), the ground leads of NJM13775, and the
B
. A logic LOW gives a current flow in the