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CMOS 4xxx Series Logic Gates

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Joined: 3 years ago
Posts: 1011
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While messing about with Hall Effect sensors, LM358 OpAmps and XOR gates (shown in post #4496), I discovered that the XOR gate input only requires a negligible current (µAs) on one or the other input to activate the output.

I was wondering if anyone with any more experience than I, knows whether, in "real-life", these XOR gate inputs should be pulled down to ground? Unfortunately, the datasheet is as clear as mud to the amateur and the schematic just shows a number of FET transistors but no internal pull-down connection.