20.4.1 Negative Logic
· Some applications will use negative logic. Effectively this is the opposite of positive logic.
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Positive Logic - a high/low voltage or current level indicates a true/false condition
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Negative Logic - a low/high voltage or current level indicates a true/false condition
· This is common in a variety of applications. Reasons include,
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- we want current to flow when things are alright, consider an E-stop.
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- a device input "floats high" so that when there is no input it turns on. This is common with many integrated circuits.
