NJM37717 New Japan Radio Co., Ltd., NJM37717 Datasheet - Page 9

• Manufacturer Part Number: NJM37717
• Description: STEPPER MOTOR DRIVER
• Manufacturer: New Japan Radio Co., Ltd.

Analog control
As the current levels can be continuously controlled by modulating the V
achieved.
Switching frequency
The motor inductance, together with the pulse time, t
The choice of motor may then require other values on the R
to obtain a switching frequency above the audible range. Switching frequencies above 40 kHz are not recom-
mended because the current regulation can be affected.
Sensor resistor
The R
choice for 415 mA max motor current at V
The peak motor current, im , can be calculated by using the formulas:
i
i
i
Heatsinking
The junction temperature of the chip highly effects the lifetime of the circuit. In high-current applications, the
heatsinking must be carefully considered.
the printed circuit board (see figure 10) or by applying an external heatsink type V7 or V8, see figure 9.
°C, for heatsinks of the type V7, V8 or a 20 cm
board copper must be connected to electrical ground.
forced-air cooling may be available to reduce the temperature rise of the circuit.
m
m
m
The Rth
The diagram in figure 16 shows the maximum permissible power dissipation versus the ambient temperature in
For motor currents higher than 500 mA, heatsinking is recommended to assure optimal reliability.
The diagrams in figures 9 and 10 can be used to determine the required heatsink of the circuit. In some systems,
= (V
= (V
= (V
S
R
R
R
resistor should be of a non-inductive type, power resistor. A 1.0 ohm resistor, tolerance
• 0.083) / R
• 0.050) / R
• 0.016) / R
j-a
of the NJM37717 can be reduced by soldering the ground pins to a suitable copper ground plane on
S
S
S
Figure 9. Heatsinks, Staver, type V7 and V8 by Columbia-Staver UK
Figure 10. Copper foil used as a heatsink
[A], at 100% level
[A], at 60% level
[A], at 20% level
R
= 5V.
2
copper area respectively. Any external heatsink or printed circuit
off
, determines the switching frequency of the current regulator.
T
, C
T
components than those recommended in figure7,
R
input, limited microstepping can be
NJM37717
1%, is a good