L6219DSA
Figure 2:
Principle Operating Sequence
Single-pulse Generator
The pulse generator is a monostable triggered on
the positive going edge of the comparator output.
The monostable output is high during the pulse
time, t
off
, which is determined by the time compo-
nents R
t
and C
t
.
t
off
= 1.1
•
R
t
C
t
The single pulse switches off the power feed to
the motor winding, causing the winding current to
decrease during t
off
.
If a new trigger signal should occur during t
off
, it is
ignored.
Output Stage
The output stage contains four Darlington transis-
tors (source drivers) four saturated transistors
(sink drivers) and eight diodes, connected in two
H bridge.
The source transistors are used to switch the
power supplied to the motor winding, thus driving
a constant current through the winding.
It should be noted however, that is not permitted
to short circuit the outputs.
Internal circuitry is added in order to increase the
accuracy of the motor current particularly with low
current levels.
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