I have a dedicated PCB for MCP23017 I-O Expanders. I will be used to manage switches when used in input mode, and ordinary LEDs when used in output mode.

Debounce in input mode is done using Bourns debounce technique (10K/0.1uF), followed by a 74HC14 Schmitt Trigger (3 ICs in all).



What would be a good capacitor value for the power connector?

It would be placed at top center; under the +/- pins on J1 main connector.

JLC has 10uF and 100uF SMD tantalum in stock as basic parts.

 

All of the chips should have 0.1uF bypass caps adjacent to the power pins.

 

All of the chips should have 0.1uF bypass caps adjacent to the power pins.

Yup, I have that already (as close as possible).

I was asking for a recommendation for the capacitor value alongside the power connector coming into the PCB.

The enclosure will be about 6 inches by 8 inches. The USB PCB will be in the center, with MCP23017 PCBs vertically along the sides. So the wires will be no longer than 8 inches.

 

What is the supply voltage?
How much current does the entire board need?

 

What is the supply voltage?
How much current does the entire board need?

It is a USB powered enclosure, no external power; so 5V with approx 300mA estimated consumption.

 

Put the 100μF on the power input.