Posted on May 17, 2011 at 13:09There is no such thing as a 5V STM32.
The only 5V ARM7+ I know of is this guy:
http://focus.ti.com/docs/prod/folders/print/tms470plf111.html Now, what kind of system is this? What was the MCU in there? How many of wich peripheral you specifically need? And of course, is energy saving a factor in your design?
Knowing the above, there acn be ways to use a 3.3V MCU in a 5V system. First, you need to supply 3.3V to the MCU. Using a LM3940IT-3.3 or similar, the transition is easy.
Now, interfacing the peripherals from 3.3V to 5V can be a lot more tricky. There is digital buffers that offers voltage translation on most bus types out there. If you specify wich, I may offer some recommendations. There is even 5V input tolerant pins on the STM32, and depending on the device you're outputing to there is a change a 4.0V driven STM32 might be able to logically interface directly.
Of course, changing CPU and adapting voltage levels may be a good point to re-design the device with lower-priced 2.5V/3.3V parts.
