The discussion focuses on calculating the fan-out resistance of N gates in parallel, specifically using the formula Rtotal = (1/N) Rgate. With a load resistor of 10k Ohms, the output voltage Vout is derived using Ohm's law, leading to the conclusion that a maximum of ten gates can be connected without exceeding the threshold of 1.7v. The 10k load resistor refers to the input resistance of each gate, which decreases as more gates are connected in parallel.
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The combined resistor value of N gates in parallel is: Rtotal = (1/N) Rgate
The load resistor decrease as we connect more input gates, let us calculate the logic-1 level with a load resister of 10k Ohms. Using Ohm's law:
Vout = 3.5v * (10,000 / N) / [ 1000 + (10,000 / N) ] > 1.7v
( where Vsource = 3.5, Rsource = 1000 and the threshold for indeterminate values is 1.7v )
we get: 1700N < 18,000, so the maximum number we can connect is ten or so.
gs408 said:Hi, pretty basic question, I'm looking through some notes and it says:
What does the 10k load resistor refer to? Is it the resistance of one gate? Or the combined resistance of multiple gates? Just wanted to clarify.
Thanks.