NJM37770 New Japan Radio Co., Ltd., NJM37770 Datasheet - Page 8

• Manufacturer Part Number: NJM37770
• Description: STEPPER MOTOR DRIVER
• Manufacturer: New Japan Radio Co., Ltd.

NJM37770
Analog control
As the current levels can be continuously controlled by modulating the V
input, limited microstepping can be
R
achieved.
Sensor resistor
The R
resistor should be of a noninductive type power resistor. A 0.5 ohm resistor, tolerance
1%, is a good
S
choice for 800 mA max motor current at V
= 5V.
R
The peak motor current, i
, can be calculated by using the formula:
m
i
= (V
• 0.080) / R
[A], at 100% level
m
R
S
External recirculation diodes
Recirculation diodes must be connected across each motor terminal and the supply voltage, V
. The anodes shall
MM
be connected to the motor terminals and the cathodes to the V
voltage. Ultra-fast recovery diodes should be
MM
used for maximum performance and reliability.
Figure 8. Copper foil used as a heatsink
Figure 9. Principal operating sequence.