+3.3V or 5V

Created Tue, 31 May 2011 23:03:44 +0000 by Jacob Christ

Jacob Christ

Tue, 31 May 2011 23:03:44 +0000

I'm looking at buying some shields to use with the chipKIT and I'm noticing they come in 3.3V and 5V flavors. I'm assuming that the PIC32 is running with 3.3V I/O and probably has 5V tolerant inputs on at least some pins...

I'm assuming I should get the 3.3V shields, but I'm not real sure, anybody know the answer to this?

Jacob

GeneApperson

Wed, 01 Jun 2011 22:16:45 +0000

The PIC32 part operates the i/o at 3.3V, so all outputs will have a 3.3V logic level. All of the digital pins are 5V tolerant, the analog pins are not explicitly 5V tolerant, so the chipKIT boards have a 200 ohm resistor to limit current and a diode to clamp the pin voltage to the 3.3V rail to protect the chip from 5V inputs (the PIC32 part absolute max pin voltage is 4V).

If possible, you should get a 3.3V shield, as it will have the best chance at complete compatibility. I designed to board to be safe to use with 5V shields, and generally 5V shields should work, but get a 3.3V one if you have the option.

Gene Apperson Digilent