The MCF52259 Data Sheet says (Table 2.1, page 23) that the RAM standby supply voltage (Vstby) must be 1.8V to 3.5V. While Table 2.6 (pg 28( says that Standby voltage Vstby must be 3.0V to 3.5V. I assume this means that 1.8V is OK if you aren't running, but not if you are.
My interest is not in the RAM, but the RTC, which is also fed from Vstby. Does it work at < 3.0V? The Data Sheet doesn't mention the RTC. The '59 Reference Manual has a whole chapter on the RTC, but doesn't say how it gets its power.
So, can the RTC keep time at less than 3.0V?