Dear all,
I am learning digital electronics and for a long time I have played with logic IC's but there's something that I really need to know.
Firstly, I am working with CMOS chips, specifically the 74HC series of chips.
What I want to know is, should I add resistors at the Vcc or the logic Inputs of these chips? I have no idea what the current should be at these places. The IC's seem to work without them. The datasheet says that the "Input diode current" should be 20mA, but what is Diode Input ? is it just the inputs? Why call it diode? Also it says that at 6V, the "Quiescent Supply Current" is 4uA at 25C and 40uA from -40 to 85C. This information seems crazy.
Anyway. how do I calculate the resistors to use, in case they're needed? It seems also that the inputs have very high resistance and so maybe resistors are not needed at inputs.
Please let me know
Much appreciated
Thank you,
Paulo
I am learning digital electronics and for a long time I have played with logic IC's but there's something that I really need to know.
Firstly, I am working with CMOS chips, specifically the 74HC series of chips.
What I want to know is, should I add resistors at the Vcc or the logic Inputs of these chips? I have no idea what the current should be at these places. The IC's seem to work without them. The datasheet says that the "Input diode current" should be 20mA, but what is Diode Input ? is it just the inputs? Why call it diode? Also it says that at 6V, the "Quiescent Supply Current" is 4uA at 25C and 40uA from -40 to 85C. This information seems crazy.
Anyway. how do I calculate the resistors to use, in case they're needed? It seems also that the inputs have very high resistance and so maybe resistors are not needed at inputs.
Please let me know
Much appreciated
Thank you,
Paulo