HCTL-1100 Datasheet, PDF (26/40 Pages) Agilent(Hewlett-Packard) – General Purpose Motion Control ICs

Each time an index pulse occurs,
the internal commutator ring
counter is reset to 0. The ring
counter keeps track of the current
position of the rotor based on the
encoder feedback. When the ring
counter is reset to 0, the
Commutator is reset to its origin
(last phase going low, Phase A
going high) as shown in
Figure 10.
The output of the Commutator is
available as PHA, PHB, PHC, and
PHD. The HCTL-1100’s
commutator acts as the electrical
equivalent of the mechanical
brushes in a motor. Therefore, the
outputs of the commutator
provide only proper phase
sequencing for bidirectional
operation. The magnitude
information is provided to the
motor via the Motor Command
and PWM ports. The outputs of
the commutator must be com-
bined with the outputs of one of
the motor ports to provide proper
DC brushless and stepper motor
control. Figure 9 shows an
example of circuitry which uses
the outputs of the commutator
with the Pulse output of the PWM
port to control a DC brushless or
Figure 8. Codewheel Index Pulse Alignment.
Figure 9. PWM Interface to Brushless DC Motors.
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Figure 10. Commutator Configuration.