MM74HC is a high-speed CMOS with high speed, low power consumption and strong anti-interference ability.
The document explains that the MM74HC family offers speed performance similar to low-power Schottky TTL while maintaining the low power and high noise immunity of CMOS. It specifies that standard HC-CMOS AC characteristics are measured at supply voltages of 2.0V, 4.5V, and 6.0V for various temperature ranges.
The text provides methods for calculating propagation delays under different conditions not covered by the data sheet. This includes adjustments for power supply voltage variations using normalized curves and calculations for capacitive loading effects on standard and bus driver outputs.
The specified input signals have a rise and fall time of 6 ns.
Propagation delays increase by about two to three times as the voltage drops from 5V to 2V.
The extra transition time should result in less than a 2 ns increase in circuit delay.