xuexucheng
Full Member level 2
For unused input pins of CMOS logic gates circuit or other digital CMOS circuit, how to handle them? I know they must be conneted to logic 1 or logic 0. But shall we connect direct to ground or power, or shall we connnect to ground or power via resistors? I like to connect direct to ground, because this is simple and there is no resistor, so the comonents number is low, and the caculation reliability should be high. However, I find some method in a datasheet of UT54AC164245, they give "It's good design practice to tie the unused input to VSS via a resistor to reduce noise susceptibility. The resistor protects the input pin by limiting the current from high going variations in VSS."
by limiting the current from high going variations in VSS --- I do not understand the current. Could you give some your opinion?
by limiting the current from high going variations in VSS --- I do not understand the current. Could you give some your opinion?