I am working on a project where I need a lot ( about 90 ) of output pins. Obviously the UNO does not have enough pins and even the Mega isn’t quite there. So I found the MCP23017 IC online, it is a 16-Bit I/O Expander with a Serial Interface. Multiple of these IC’s can be connected to the arduino to get up to 128 extra I/O pins.
My problem is that the maximum current that each of the IC’s can output is 150 mA, which means that I can only get about 9.375 mA per pin (150 / 16 = 9.375) . Can I increase this output current by stacking two of these IC’s in parallel? Or can you recommend something better to get more pins?
And what is the current that is needed to light a standard 3mm LED, because most of the pins will be used to light leds.
Find the attached datasheet for the IC.
Please help me.
MCP23017.PDF (948 KB)