MC68HC908MR8 Datasheet, PDF (160/372 Pages) Motorola, Inc – Microcontrollers

Pulse-Width Modulator for Motor Control
complimentary operation is in use, the odd OUTx bits are inputs to the
dead-time generators as shown in Figure 9-14. Dead-time is inserted
whenever the odd OUTx bit toggles as shown in Figure 9-19. Although
dead-time is not inserted when the even OUTx bits change, there will be
no dead-time violation as shown in Figure 9-20.
Setting the OUTCTL bit does not disable the PWM generator and current
sensing circuitry. They continue to run, but are no longer controlling the
output pins. In addition, OUTCTL will control the PWM pins even when
PWMEN = 0. When OUTCTL is cleared, the outputs of the PWM
generator become the inputs to the dead-time and output circuitry at the
beginning of the next PWM cycle.
NOTE:
To avoid an unexpected dead-time occurrence, it is recommended that
the OUTx bits be cleared prior to entering and prior to exiting individual
PWM output control mode.
UP/DOWN COUNTER
MODULUS=4
DEAD-TIME = 2
PWM VALUE = 3
OUTCTL
OUT1
OUT2
PWM1
PWM2
PWM1/PWM2
2
2
DEAD-TIME
DEAD-TIME INSERTED AS PART OF
NORMAL PWM OPERATION AS
CONTROLLED BY CURRENT
SENSING AND PWM GENERATOR
DEAD-TIME INSERTED DUE
TO SETTING OF OUT1 BIT
2
DEAD-TIME INSERTED
DUE TO CLEARING OF
OUT1 BIT
Figure 9-19. Dead-Time Insertion During OUTCTL = 1
Technical Data
160
MC68HC908MR8 — Rev 4.1
Pulse-Width Modulator for Motor Control (PWMMC) Freescale Semiconductor