Electronic – 74 Series Logic Power switching with Gnd? (74Hc86)

digital-logicpower

I'm trying to cut power to the chip to "disable" all outputs without needing to know the input values or changing them. What happens if I use a NPN transistor to let the GND pin float and pull it to GND if the transistor switches on? Would that work? I'm trying to use a npn because my circuit has one unused channel in an ULN2003 and I'm trying to reduce my component count.

Best Answer

The inputs to the chip will remain active and more than likely any "low" inputs will "power" the ground of the 74HC86 via protection diodes on the inputs. I don't think it will work.