MC68HC708MP16 Datasheet, PDF (153/398 Pages) Freescale Semiconductor, Inc – Microcontrollers

Pulse Width Modulator for Motor Control (PWMMC)
deadtime interval, the load voltage near a current zero crossing is
somewhere between the high and low levels.
T
B
T
B
DEADTIME
PWM TO TOP
TRANSISTOR
POSITIVE
CURRENT
PWM TO BOTTOM
TRANSISTOR
LOAD VOLTAGE WITH
HIGH POSITIVE CURRENT
LOAD VOLTAGE WITH
LOW POSITIVE CURRENT
LOAD VOLTAGE WITH
HIGH NEGATIVE CURRENT
LOAD VOLTAGE WITH
LOW NEGATIVE CURRENT
T = DEADTIME INTERVAL BEFORE ASSERTION OF TOP PWM
B = DEADTIME INTERVAL BEFORE ASSERTION OF BOTTOM PWM
Figure 9-21. Output Voltage Waveforms
NEGATIVE
CURRENT
Each ISx pin is sampled twice in a PWM period. The values are stored
in the DTx bits in the fault acknowlege register. The DTx bits are a timing
marker to indicate when to toggle between PWMVAL register. In the low-
current condition immediately before a current zero crossing, the two
DTx bits in a pair have dissimilar values. Software can then set the
IPOLx bit to toggle PWMVAL registers before the zero crossing ocurs.
MC68HC708MP16 — Rev. 3.1
Freescale Semiconductor Pulse Width Modulator for Motor Control (PWMMC)
Technical Data
153