Hysteresis on Input of Cypress Quantum38K CPLDs | Cypress Semiconductor
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Hysteresis on Input of Cypress Quantum38K CPLDs
Do Quantum38K CPLDs have hysteresis on the inputs?
Quantum38K CPLD's do not have explicit input hysteresis, but the effect of the bus hold circuit (if enabled) on the input may look like hysteresis. Bus hold can be approximated as a current source. As the input rises, bus hold will continue to pull low. Eventually, the input reaches the bus hold trip point and the output changes state. That means it switches from pulling low to pulling high. This change in direction of the bushold current together with the output impedance of the driver will cause a "jump" in the input voltage which looks a lot like hysteresis.
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