MCF5213 external clock and PWM issue

[pmrshudson]

I'm using a MCF5213 with an external master clock. I'm also using one of the 5213 PWM outputs to drive a MOSFET to control the speed of a fan. If I stop the master clock, I notice that the PWM will continue to run. I'd like the PWM to stop when the master clocks stops. Why does the PWM continue to run, and how can I get it to stop when the master clock is halted?

[RichTestardi]

When you stop the external clock (or even before), can you examine SYNSR and see where the MCU thinks the clock is coming from?  Is EXTOSC always set, and OCOSC/CRYOSC clear?  There is loss of clock circuitry (SYNCR->LOCEN), to automatically switch clocks or reset the MCU, but the data sheet seems to imply is disabled when running off an external clock.  See Reference Manual section 6.8.4.8.