Didi wrote...
Jim wrote...
How much does it get? I would expect low enough so the parts will
be in spec over temperature, but can you give some figure? I am
sure I have used this configuration and I never had any trouble
out of it, but I have not been looking for the last milliwats.
Never noticed a part getting hot because of that, though.
I wish Jim would give us a link or thread title, I can't find the
post he's referring to. TI's 74hct14 datasheet has a plot of the
supply current, and it's only 0.1mA with a 3.3-volt logic input,
for the extreme case of a 5.5-volt supply. If you assume a wimpy
2.8-volts (degraded 3.3V input) it's 0.15mA, not what most people
call an ENORMOUS current. (That is, unless you designed for the
long-life battery-operated field, as I did for 17 years, where
our entire budget to operate 200 ICs was often about 150uA.)
TI specs the maximum current for a HCT14 single 2.4-volt input as
2.9mA and the maximum for a VHCT14 is 1.5mA with 3.4V input. The
real-world currents for both families will be much lower. Neither
is a deal-breaker for most circuits, since even 15mW dissipation
would usually not be a problem. It can't lead to overheating!
BTW, Jim's suggested AVC logic series can't work to convert 3.3
volt logic to nice 5 volt swings, as Yuriy complained, because
the AVC stuff can't be operated on a 5-volt supply. The 3.3V
output of a AVC logic gate would simply pass the problem on to
the next HCTxxxx 5V logic gate.
Dimiter Popoff, Transgalactic Instruments
http://www.tgi-sci.com
Interesting company name!