[sdiy] Another new hard to find part....

[Scott Gravenhorst]

"Roy J. Tellason" <rtellason at blazenet.net> wrote:
>On Tuesday 06 July 2004 11:30 am, Scott Gravenhorst wrote:
>
>> >What I don't understand is the point of numbers like 74HC4xxx,  where
>> > they're (apparently?) giving you the function of a 4000 series part but
>> > putting a 74 in front of it?  Maybe I'm just missing the point as I have
>> > not yet seen a databook for these newer families.
>
>> There are small differences.  For example, I just learned that the 74HC4046
>> is basically the same as a CD4046, (micro power PLL), but the VCO in the
>> 74HC part tops out at a much higher frequency.
>
>Now that's an interesting tidbit!	:-)
>
>> I haven't researched the whole family, but would guess that there are
>> performance advantages of many 74HC parts over CD4xxxx.
>
>I can find the occasional datasheet out there on the 'net,  but really 
>probably should get my hands on a book that covers those parts...
>
>> Also beware the power requirements.  Some of the 74HC parts are 5 volt
>> limited.
>
>Yeah,  _that_ makes no sense to me,  why the heck they'd do that!
>
>> >And I remember reading somewhere that the whole 4000 series was going
>> > away. Is this the case?  If,  as I have the impression of but am not
>> > sure,  the 74HC and similar parts will only work with lots lower voltage
>> > supplies,  that sure is going to limit some options.  I kind of liked the
>> > idea of a logic family which would run on 15V or so,  and sometimes even
>> > wished that it were higher! (Like being able to run something off a split
>> > supply like what's typical for op amps.)
>
>> Not only will CD4xxxx work to 15 volts (some parts to 18), they will also
>> work down to 3 volts.
>
>True,  though this isn't an area where I've taken advantage of it yet.
>
>> I have run several CD4xxxx based circuits from +/- 8 volts without problems. 
>> I just make sure all of the parts in the design are speced to 18 volts.
>
>What's that,  the "B" series?

"B" at the end of the number just means "buffered".  You can only know the
voltage range by getting the data sheet.  I have a habit of downloading the PDF
files for everything I use and keeping them here.  "UB" at the end means
unbuffered and have some interesting uses.  Eg., the 4069UB can be used as a
"linear amplifier" (see data sheet) which works kind of like an opamp.  It has
an interesting was of distorting, more like vacuum tube soft clipping.

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