I/O Pin protection

[LBdgWgt]

Hi all,

I have a question about the I/O pin protection og HCS12 microcontrollers. I am designing additional board which will be used along the CARDS12 board from elektronikladen, and I want to make some interface circuit for I/O pins protection.
Does anybody know that HCS12 I/O pins are already protected by diodes (connected to GND and VCC) for protection against overvoltage?

Thanks for any answer,

[Steve]

Hi,

 A good resource is AN2727 which talks about good hardware practice. http://www.freescale.com/files/microcontrollers/doc/app_note/AN2727.pdf

 If you 'exceed' VDD or GND then you will create injection currents for which there are specs and these are also discussed in the app note.