I've got a circuit specifying a "74HCT138" and can find a 74LS138 at Jaycar, is this a compatible component?
Thanks in advance!
HCT vs LS..
Nov 05, 2005
5 Replies
The HCT is CMOS and the LS isn't, there are differences in speed, voltage levels and power consumption. You can try it but it maybe erratic
**Same basic function, but fundamental differences in performance. Best not to substitute, unless the circuit is uncritical.
Trevor Wilson
www.rageaudio.com.au
Thanks to both who replied :)
I'd guess timing probably ISNT too criticial, but for the sake of a day or
2, i'll order the correct parts from farnell :)Thanks again!
For all but the most critial aplication they should be compatible, although usually it's the other way around. The HCT series is designed to be a low power high speed CMOS replacement for the 74LS series, as it has TTL compatible voltage levels, that's what the "T" stands for. Best to get the same part if you can though, substituting parts may work at first try, but unless you try it over the full performance envelope you won't really know.
Dave :)
sometimes. google for the specifications.
Bye.
Jasen
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