What is the fastest 7400 series logic family?

Is 74VHC* faster than 74AHC*?

This list does not seem to be in any particular order: http://en.wikipedia.org/wiki/7400_series


2 Answers 2


From the TI Logic Guide (2017 version) AUC, AVC and ALVC are fastest. LVC is next fastest. LVA, AC and AHC are slower, but similar. HC is slowest.

VHC (Fairchild, On, NXP) is similar to AHC (TI). So they are the same. Check the respective data sheets depending on voltage, load, etc.


Previous answer is not fully correct because there is some issue to consider first. First there is two-three key categories which define "faster then" regarding:

  • Propagation/delay of input signal known as Tpd that is usually marketed by manufacturers and vendors, and it is usually measuring smallest time delay of signal on lowest possible capacitance setup on defined (max operating) Voltage.If it state XX on 15pF or YY on 50pF then it is OK, but when they provide results from 5pF or less it is practically unusable info.

  • Signal rise and fall time Tr/Tf usually measured from 10-90% of Vi-Vo if much more usefully information that define real speed, but often you can not see that info.
    For example faster are 74ABT, 74AC, 74F that have Tr/Tf in on 5V low as 1.3-1.7ns, and 74VHC is 2,3-3ns, 74AHC/LVC are even worse. 74AUC, AVC are near first group but on half of voltage (2-3.3V)

  • And then what is max working frequency of considered 74series device depend on its internal and external capacitance that determine max working range in MHz. For example VHC can go up to 210MHz, but AHC is limited to 150-160MHz, AC has max like 100..140MHz.

At the end considering better noise immunity, larger working frequency and higher Io current VHC is winner over AHC in 5V category. But it is not produced in C/PDIP.

p.s. VHC is originally Fairchild improvement over AC series.

  • \$\begingroup\$ I have recently measured LVC family rise/fall time, and found it to typically be under 600ps. In the past I have also noted that AC family logic had ~700ps rise time. \$\endgroup\$ Commented Aug 12, 2018 at 4:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.