Replacement for -STM32F103VBT6/STM32F103VCT6

Posted on May 17, 2011 at 13:09

Hi,

We have identified STM32F103VBT6/STM32F103VCT6 as the replacement for one of the existing MCU. The selected MCU from ST micro operates on 3.3V supply rail.In our existing design we have the MCU at 5V.

Please could you let me know if there is a drop in replacement for the 3.3V MCU from ST micro?

Posted on May 17, 2011 at 13:09

Hi ,

The STM32 series do not allow to operate at 5Volts, neither to output 5 Volts. All GPIOs are 5-Volts Tolerant, means in input only, not output. This is standard in the industry now to be able to reduce the power consumption. 5Volts Micro-controllers are still present in automotive and some industrial markets today which we address and cover by our ARM7 Portfolio : STR73x series and STR75x devices, please refer to

http://www.st.com/mcu/inchtml-pages-str730.html

Cheers,

STOne-32.

Posted on May 17, 2011 at 13:09

There 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.