ZHCSP28A July 2021 – October 2021 SN74HCS244
This device includes inputs with the Schmitt-trigger architecture. These inputs are high impedance and are typically modeled as a resistor in parallel with the input capacitance given in the Electrical Characteristics table from the input to ground. The worst case resistance is calculated with the maximum input voltage, given in the Absolute Maximum Ratings table, and the maximum input leakage current, given in the Electrical Characteristics table, using Ohm's law (R = V ÷ I).
The Schmitt-trigger input architecture provides hysteresis as defined by ΔVT in the Electrical Characteristics table, which makes this device extremely tolerant to slow or noisy inputs. While the inputs can be driven much slower than standard CMOS inputs, it is still recommended to properly terminate unused inputs. Driving the inputs with slow transitioning signals will increase dynamic current consumption of the device. For additional information regarding Schmitt-trigger inputs, please see Understanding Schmitt Triggers.