[time-nuts] Performance of 74LVC series ICs

Tim Shoppa tshoppa at gmail.com
Mon Jun 1 15:09:38 EDT 2015


The example circuits given on that webpage will be inferior in every way to
RTL and DTL logic from the 1960's, which itself is inferior to late
60's/early 70's TTL.

A good reference on how to do discrete transistor logic design from the
1960's, is TI's book "Transistor Circuit Design". I just poked around
bitsavers hoping it might be there, but didn't see it. Paper copies abound
in used bookstores.
http://www.amazon.com/Transistor-Circuit-Design-Instruments-Incorporated/dp/0070637377

There are a handful of level-shifting logic-type circuits for oddball
voltages that might still be done best using discrete transistors
especially if you don't need say the full quad of a MC1488 or MC1489.

Tim N3QE

On Mon, Jun 1, 2015 at 11:00 AM, Vlad <time at patoka.org> wrote:

>
> I am curious, how the integrated gates could be compared for those created
> on discrete elements ? Let say simple gates like this:
>
> http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/trangate.html
>
> Regards,
> Vlad
>
>
>
> On 2015-05-31 18:23, Attila Kinali wrote:
>
>> On Sun, 31 May 2015 14:06:26 -0400
>> Dan Watson <watsondaniel3 at gmail.com> wrote:
>>
>>  Has anyone used or experimented with the 74LVC series of ICs? I have
>>> found
>>> them quite useful in projects. Supply voltage of 2-5V, and two inverters
>>> or
>>> a single gate or flip flip in a SOT package. They make for much cleaner
>>> layouts than large DIPs.
>>>
>>
>> Yes, quite a few of those. After CPLDs and FPGAs replaced all of the
>> more complex 74xxx's, people realized that most projects do not need
>> 4 NAND gates at one spot, but rather single ones here and there
>> (a schmitt-trigger for signal conditioning, an AND gate to couple two
>> enable lines,...).
>>
>>  I'm wondering if they are acceptable replacements for 74HC, AC, etc in
>>> timing circuits.
>>>
>>
>> I have never used any of the LVC in a timing circuit, but i would
>> guess they are not worse than the AC. Also they have the advantage of
>> having single gates per package, which helps minimizing cross coupling
>> between different signal paths.
>>
>> BTW: [1] may contain some interesting data for you. Especially as it
>> compares different manufacturers too.
>>
>> Looking at [2], the ALVC family would probably be also worth a look.
>>
>>                                 Attila Kinali
>>
>>
>> [1] "Low Voltage Logic Designers Guide", Ti, 1996
>> http://www.ti.com/lit/ml/scba010/scba010.pdf
>>
>> [2] "Logic Guide", Ti, 2014
>> http://www.ti.com/lit/sg/sdyu001aa/sdyu001aa.pdf
>>
>
> --
> WBW,
>
> V.P.
>
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