MC68HC708MP16 Datasheet, PDF (150/398 Pages) Freescale Semiconductor, Inc – Microcontrollers

Pulse Width Modulator for Motor Control (PWMMC)
During deadtime, load inductance distorts output voltage by keeping
inductive current flowing through the diodes. Inductive distortion either
lengthens or shortens the pulse width by one deadtime interval,
depending on current direction. This deadtime distortion then either
increases or decreases the averaged sinusoidal output voltage.
DESIRED
VOLTAGE
NEGATIVE
CURRENT
POSITIVE
CURRENT
Figure 9-19. Sinusoidal Distortion of Load Voltage
In complementary channel operation, either the odd-numbered or the
even-numbered PWMVAL registers control the pulse width at any given
time. For a given PWM pair, whether the odd or even PWMVAL registers
are active depends on either:
• The state of the current-sensing pin, ISx, for that driver, or
• The state of the output polarity bit, IPOLx, for that driver
Technical Data
150
MC68HC708MP16 — Rev. 3.1
Pulse Width Modulator for Motor Control (PWMMC) Freescale Semiconductor