NJM3775D2 NJR, NJM3775D2 Datasheet - Page 9

• Manufacturer Part Number: NJM3775D2
• Description: IC STEPPER MOTOR DVR DUAL 22-DIP
• Manufacturer: NJR
• Type: Stepper Motor Controller/Driverr

Specifications of NJM3775D2

• Applications: Stepper Motor Driver, 2 Phase
• Number Of Outputs: 1
• Current - Output: 750mA
• Voltage - Load: 10 V ~ 40 V
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -20°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: 22-DIP (0.400", 10.16mm)
• Product: Stepper Motor Controllers / Drivers
• Operating Supply Voltage: 7 V
• Supply Current: 70 mA
• Mounting Style: Through Hole
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

NJM3775
Full-step mode.
Both windings are energized at all the time with the same current, I
= I
. To make the motor take one step, the current
M1
M2
direction (and the magnetic field direction) in one phase is reversed. The next step is then taken when the other phase current
reverses. The current changes go through a sequence of four different states which equal four full steps until the initial state is
reached again.
Half-step mode.
In the half-step mode, the current in one winding is brought to zero before a complete current reversal is made.
The motor will then have taken two half steps equalling one full step in rotary movement. The cycle is repeated, but on the other
phase. A total of eight states are sequenced until the initial state is reached again.
Half-step mode can overcome potential resonance problems. Resonances appear as a sudden loss of torque at one or more
distinct stepping rates and must be avoided so as not to loose control of the motor´s shaft position.
One disadvantage with the half-step mode is the reduced torque in the half step positions, in which current flows through one
winding only. The torque in this position is approximately 70 % of the full step position torque.
Modified half-step mode.
The torque variations in half step mode will be elimi-nated if the current is increased about 1.4 times in the halfstep position. A
constant torque will further reduce resonances and mechanical noise, resulting in better performance, life expectancy and
reliability of the mechanical system.
Modifying the current levels must be done by bringing the reference voltage up (or down) from its nominal value correspondingly.
This can be done by using DACs or simple resistor divider networks. The NJM3775 is designed to handle about 1.4 times higher
current in one channel on mode, for example 2 x 500 mA in the full-step position, and 1 x 700 mA in the half-step position.