Datasheet

By substituting equations 1 and 2 into equation 3
and solving for the value of R1 the following equa-
tions for the external componentscan be derived :
1
R1 = ( – 2) R
IN
(4)
DC
T1
C1 = (5)
0.69 R1
Looking at equation 1 it can easily be seen that the
minimumpulsewidthof T2 will occurwhenthe value
of R1 is at its minimum and the value of R1 at its
maximum. Therefore, when evaluating equation 4
the minimum value for R1 of 700Ω (1 KΩ –30%)
should be used to guarantee the required pulse
width.
Figure 1 : Oscillator Circuit and Waveforms.
APPLICATIONS INFORMATION
The circuits shown in figure 2 use the L6506 to im-
plement constant current drives for steppermotors.
Figure 2 shows the L6506 used with the L298 to
drivea 2phasebipolarmotor. The peakcurrent can
be calculated using the equation :
V
ref
I
peak
=
R
sense
The circuit of Fig.2 can be used in applications re-
quiring different peak and hold current values by
modifying the reference voltage.
TheL6506may beusedtoimplement eitherfullstep
or half step drives. In the case of 2 phase bipolar
stepper motor applications, if a half step drive is
used,the bridge requires an additionalinput to dis-
able the power stage duringthe half step. If used in
conjunctionwith the L298 the enableinputs may be
used for this purpose.
For quaddarlingtonarray in 4 phaseunipolarmotor
applications half step may be implemented using
the 4 phase inputs.
The L6506 may also be used to implement mi-
crostepping of either bipolar or unipolarmotors.
L6506 -L6506D
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