L6285
These two channels drive two unipolar stepper
motors in chopping mode. The basic channel con-
figuration is shown in Fig 4. by considering well
known the PWM Current Control Loop behaviour
here below only particular trick are underlined.
During DM3 off period the low side DMOS DM1
and DM2 are switched on to reduce the power
dissipation.
Figure.4: Unipolar motor driver CHA (or CHB)
The drain overvoltages generated because of the
stray inductance of the motor windings are limited
by connecting the DZ1 external zener diode to the
clamp pin.. The diodes CL1 and CL2 are inte-
grated as far as the CL3 diode which limits the
negative voltage at pin COM1.2. An internal RC
network (1µs) is realized to filter the sensing re-
sistor signal.
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