74hct series

[e44-72]

I bought a cmos 4081 quad 2 input AND gate IC and its 74hct equivelent 74hct08.
In my projects I always go for the cmos 4000 series and use a 9v pp3 battery as they can take from 3-15v
However I thought 74hct was a replacement for 74ls (TTL) and would therfore not function if more than 5v was applied. I gave the 74hct08 9v power supply like the 4000 series and it appeared to function ok other than the fact the pinout was different to the 4000 series (same as ttl pinout)
Can someone explain why the 74hct ic functions still when more than 5v is applied?

 

[Bloodninja]

thats because the 74hct has the letter 'c' in it, which indicates that the 74hct series is designed to be compatible with CMOS circuits, whilst the 74LS isnt.

 

[e44-72]

Ok, thank you for the information. So does that mean that the 74hct series can take up to 15v like the 4000 series?

 

[ronsimpson]

You need to look at the data sheets!
From the data sheet HCT08 max=7V normal 4.5 to 5.5volts. It might work this time, or for a while, but.....

 

[e44-72]

ok that helps.
so your saying that if I applied the 9v on the ic for any longer it may burn it out.

 

[ronsimpson]

zap....crack....smoke

 

[crutschow]

Look at the Absolute Maximum Ratings or Limiting Value table on the data sheet. Never exceed those ratings unless you like dead ICs.

The 74Cxx series will work up to 15V supply voltage.