[PIC18F4520] Power Supply issue

[Enrique Perez (Gast)]

Hello,

Reading the datasheet, it says that the recommended power supply is 5v. 
However this PIC is going to be connected to a 3v3 FPGA bank, and I am 
wondering if there is any way to configure the I/O pins to have 
Vout(max)=3v3 powering the chip with 5v. Is it possible?

Thanks

[Hurst (Gast)]

The voltage on the IO Pins is always the same as the supply voltage. If 
you supply the Pic with 5V, then there is no way to get the IO level to 
3.3V.

You can use a PIC18LF4520 which can be powered with 3.3V. But with only 
3.3V the PIC cant be clocked with the full frequency. See Datasheet page 
326.

[Oleg A. (oga)]

If your FPGA has 5V tolerant pins, your stuff will work without any 
modification. The only drawback will be a lower SNR.