HCTL-1101 Datasheet, PDF (21/40 Pages) AVAGO TECHNOLOGIES LIMITED – General Purpose Control ICs Position and Velocity Control Low Power CMOS

Figure 4. Motor Command Port Output.
When any Control mode is being executed, the unadjust-
ed internal 2’s-complement motor command is written to
R09H. Because of the hardware limit on the linear range
(64H to 9CH, ± 100D), the PWM port saturates sooner
than the 8-bit Motor Command port (00H to FFH, +127D
to –128D). When the internal motor command saturates
above 8 bits, the PWM port is saturated to the full ± 100%
duty cycle level. Figure 5 shows the actual values inside
the PWM port. Note that the Unipolar flag, F2, does not
affect the PWM port.
For commutation of brushless motors with the PWM port,
only use the Pulse pin from the PWM port as the commu-
tator already contains sign information. (See Figure 9.)
The PWM port has an option that can be used with H-
bridge type amplifiers. The option is Sign Reversal Inhibit,
which inhibits the Pulse output for one PWM period after
a sign polarity reversal. This allows one pair of transistors
to turn off before others are turned on and thereby avoids
a short across the power supply. Bit 0 in the Status register
(R07H) controls the Sign Reversal.
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