Difference Between 74HCxx and 74LSxx digital logic integrated circuit

Hi Jaya welcome to CircuitDigest Forums,

Blindly speaking the 74HCXX is the modern day replacement for the old  74LSXX ICs. Since the 74HCXX uses MOSFET technology it can operate in a wide range of voltage at higher frequencies compared to the 74LSXX series that works on transistor technology.

So the reason that some circuits particularly need 74HCXX is that they might have a different operating voltage other than +5V or might have to work with higher frequencies. For instance in a 3.3V system you cannot use a 74LCxx you have to use a 74HCxx

Hope this helps !!!

Thanks for answering aswith now I understand the difference.

But the problem is that my local vendor only supplies 74LSxx IC's, so can I use them on my 5V circuits?

Most probably yes, but I am not very sure because I do not know where you are trying to use them.

I remember using these 74LSxx gates extensively during my school days since my lab  did not have an alternative. Just maintain a regulated supply voltage of 5V and they should work fine. If you are dealing with fast switching (higher frequencies) then moving to a 74HCxx series should be considered.