Application information
2.6
V
S
, V
SS
, V
Ref
The circuit withstands any order of turn-on or turn-off of the supply voltages V
S
and V
SS
.
Normal dV/dt values are then assumed.
Preferably, V
Ref
should be tracking V
SS
during power-on and power-off if V
S
is established.
3
Application information
Some stepper motors are not designed for continuous operation at maximum current. As the
circuit drives a constant current through the motor, its temperature might increase
exceedingly both at low and high speed operation. Also, some stepper motors have such
high core losses that they are not suited for switch mode current regulation.
Unused inputs should be connected to proper voltage levels in order to get the highest noise
immunity. As the circuit operates with switch mode current regulation, interference
generation problems might arise in some applications. A good measure might then be to
decouple the circuit with a 100 nF capacitor, located near the package between power line
and ground. The ground lead between R
s
, and circuit GND should be kept as short as
possible. A typical application circuit is shown in
Note that C
t
must be NPO type or
similar else. To sense the winding current, paralleled metal film resistors are recommended
(R
s
).
Figure 5.
Typical application circuit
AM15162v1
Doc ID 4970 Rev 4
9/12
STMICROELECTRONICS [ STMICROELECTRONICS ]
