HCTL-1101 Datasheet, PDF (25/40 Pages) AVAGO TECHNOLOGIES LIMITED – General Purpose Control ICs Position and Velocity Control Low Power CMOS

Figure 7.Index Pulse Alignment to Motor Torque Curves.
Each time an INDEX pulse occurs; the internal commuta-
tor 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 Com-
mutator 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-1101’s Commutator acts as the
electrical equivalent of the mechanical brushes in a mo-
tor. Therefore, the outputs of the Commutator provide
only proper phase sequencing for bidirectional opera-
tion. The magnitude information is provided to the mo-
tor via the Motor Command and PWM ports. The outputs
of the commutator must be combined 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 brush-
less or stepper motor. A similar procedure could be used
to combine the commutator outputs PHA-PHD with a lin-
ear amplifier interface output (Figure 16) to create a linear
amplifier system.
The Commutator is programmed by the data in the fol-
lowing registers. Figure 10 shows an example of the rela-
tionship between all the parameters.
25