My application, shown in the diagram below, will have 12V/GND control lines that will arrive at the gate input pins as 'high' state or 'low' state. Datasheets has two values for input current: 10mA (max rating) and 0.1uA (as static characteristics).
The external board switches belong to a board that has been used for many years and cannot be modified. The switched signals (between ground or high Z) will are connected to the gates board by a connector. Every gate input has its own pull up resistor that will connect to the switch after boards interconnection.
I focused the discussion on any pins input current. I would like to know the correct way to understand this information and whether I am handling it correctly.
My question is: What is the proper pullup resistor value in order to limit the current as is needed.
I have chosen logic gate devices in order to work with input voltages as 12V: NOR, AND, NOT, etc. When reading datasheet I can see the maximum ratings and electrical characteristics tables. This is an OR datasheet information:
Table is From here
I'm worried about max input current Iin that datasheet tables tell us to be 0.1uA.
Does it means that I must be limiting the input current to this value: 0.1uA?
I have been testing my logic function. As max Vin = 12V, I put a serial resistor between 12V pin and logic gate input pin. So current will be limited to R = 12V/I. I test different values for R allowing to work with 2mA, 1mA and 0.6mA and application stills working normally during the tests time. But I wondered if the correct way is to get Iin less than 0.1uA. So this means a too much bigger resistor value, more than 20 megaOhms! Has this approach any sense? Please if my argumentation is wrong let me know.
Taking datasheet and calculations into account; what input current value would you allowing to be driven through input pin? What resistor value would you choose?
NOTE: I have chosen this Texas Instruments families looking for family that allows working with 12V control signals at their inputs and their outputs as high state. I also choose devices that have more than one gate. I will use these outputs for activate reed relays, but I will connect the outputs to a driver, and driver outputs go to the coil relays (concretely to the coil negative terminal). Image is from CD4073B and CD4081B datasheet. Datasheet here