Standard CMOS inputs are high impedance and are typically modeled as a resistor in parallel with the input capacitance shown in the Electrical Characteristics. The worst case resistance is calculated with the maximum input voltage, shown in the Absolute Maximum Ratings, and the maximum input leakage current, shown in the Electrical Characteristics, using Ohm's law (R = V ÷ I).

Signals applied to the inputs need to have fast edge rates, as defined by Δt/Δv in the Recommended Operating Conditions to avoid excessive current consumption and oscillations. If a slow or noisy input signal is required, a device with a Schmitt-trigger input should be used to condition the input signal prior to the standard CMOS input.