Searching \ for '[PIC]: 16F84A - 4MHz or 20MHz?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/devices.htm?key=16F
Search entire site for: '16F84A - 4MHz or 20MHz?'.

Exact match. Not showing close matches.
PICList Thread
'[PIC]: 16F84A - 4MHz or 20MHz?'
2000\11\06@131250 by Bill Westfield

face picon face
   I don't want to run a 4MHz chip at 20MHz. But if I bought 4MHz chips
   that are actually 20MHz chips I would like to KNOW. :o)

I think it's unlikely that chips that have actually been through the testing
procedure for 20MHz parts would be (re)marked as 4MHz parts.  What IS likely
is that long after a production line / die-shrunk design is producing chips
that will ALL run at 20MHz, only some of them will go through the testing
regime, and the rest will get labeled as 4MHz...

BillW

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use spam_OUTlistservTakeThisOuTspammitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\06@142118 by David VanHorn

flavicon
face
At 10:11 AM 11/6/00 -0800, William Chops Westfield wrote:
>    I don't want to run a 4MHz chip at 20MHz. But if I bought 4MHz chips
>    that are actually 20MHz chips I would like to KNOW. :o)
>
>I think it's unlikely that chips that have actually been through the testing
>procedure for 20MHz parts would be (re)marked as 4MHz parts.  What IS likely
>is that long after a production line / die-shrunk design is producing chips
>that will ALL run at 20MHz, only some of them will go through the testing
>regime, and the rest will get labeled as 4MHz...


So why would microchip damage their profitability, by selling you 20 MHz
chips at 4 MHz prices?  (unless they had to, because they ran out of 4 MHz
chips)

If all the chips are 20 MHz, then why not just drop the lower speed grades
from the product lineup?

Understand, I do believe that they would like to produce only 20 MHz parts
(or whatever the highest speed is) but based on many converations with many
vendors, I don't think that they are actually able to pull this off.

--
Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use .....listservKILLspamspam@spam@mitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\06@143952 by Bill Westfield

face picon face
   If all the chips are 20 MHz, then why not just drop the lower
   speed grades from the product lineup?

Like they do in the wintel pc market.  Shudder.  Ask an embedded
manufacturer how they feel about components with 6-month lifetimes,
sometime.  Dropping products from a lineup is a a terrible thing to
do, even if the new part is theoretically fully backward compatible.

BillW

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use listservspamKILLspammitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\06@144624 by David VanHorn

flavicon
face
At 11:40 AM 11/6/00 -0800, William Chops Westfield wrote:
>    If all the chips are 20 MHz, then why not just drop the lower
>    speed grades from the product lineup?
>
>Like they do in the wintel pc market.  Shudder.  Ask an embedded
>manufacturer how they feel about components with 6-month lifetimes,
>sometime.  Dropping products from a lineup is a a terrible thing to
>do, even if the new part is theoretically fully backward compatible.

If there's compatibility issues from one speed grade to the other, beyond
the xtal speed, then they can't have been produced from the same masks, and
all as intended to be 20 MHz parts.


--
Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use .....listservKILLspamspam.....mitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\06@151320 by Bob Ammerman

picon face
> So why would microchip damage their profitability, by selling you 20 MHz
> chips at 4 MHz prices?  (unless they had to, because they ran out of 4 MHz
> chips)
>
> If all the chips are 20 MHz, then why not just drop the lower speed grades
> from the product lineup?
>

It doesn't cost as much to make a chip that will go 20MHz if you don't test
it to 20MHz.

For example: Mchip could have determined that any chip that runs at, say,
8.12MHz (just to pick a number) at Vcc = 5V and Temp = 25c will also run
fine at 4MHz across temp and voltage.

Now they just have to test at 8.12Mhz and be done with it!

On the other hand, they may have to do multiple tests are various voltages
and temps to ensure 20Mhz operation across temp and voltage.

Less testing, less cost, even if the die is in actuality a 20Mhz capable
part!

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use EraseMElistservspam_OUTspamTakeThisOuTmitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\06@155309 by David VanHorn

flavicon
face
>It doesn't cost as much to make a chip that will go 20MHz if you don't test
>it to 20MHz.

Ok, I buy this.


>On the other hand, they may have to do multiple tests are various voltages
>and temps to ensure 20Mhz operation across temp and voltage.

Which still leaves us here: If the chip says 4 MHz, it may die in strange
and unexpected ways, at anything higher than 4 MHz.



I wish someone from uChip would step in and make a definitive statement..


--
Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use listservspamspam_OUTmitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\06@161807 by Bob Ammerman

picon face
----- Original Message -----
From: David VanHorn <@spam@dvanhornKILLspamspamCEDAR.NET>
To: <KILLspamPICLISTKILLspamspamMITVMA.MIT.EDU>
Sent: Monday, November 06, 2000 3:53 PM
Subject: Re: [PIC]: 16F84A - 4MHz or 20MHz?


> >It doesn't cost as much to make a chip that will go 20MHz if you don't
test
> >it to 20MHz.
>
> Ok, I buy this.
>
>
> >On the other hand, they may have to do multiple tests are various
voltages
> >and temps to ensure 20Mhz operation across temp and voltage.
>
> Which still leaves us here: If the chip says 4 MHz, it may die in strange
> and unexpected ways, at anything higher than 4 MHz.
>

Exactly, so the moral is: DON'T RUN IT ABOVE 4 MHz!!

{Quote hidden}

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use spamBeGonelistservspamBeGonespammitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\06@164320 by Harold M Hallikainen

picon face
On Mon, 6 Nov 2000 14:22:13 -0500 David VanHorn <TakeThisOuTdvanhornEraseMEspamspam_OUTCEDAR.NET>
writes:
> So why would microchip damage their profitability, by selling you 20
> MHz
> chips at 4 MHz prices?  (unless they had to, because they ran out of
> 4 MHz
> chips)
>
> If all the chips are 20 MHz, then why not just drop the lower speed
> grades
> from the product lineup?
>
> Understand, I do believe that they would like to produce only 20 MHz
> parts
> (or whatever the highest speed is) but based on many converations
> with many
> vendors, I don't think that they are actually able to pull this off.
>

       As others have pointed out, the chips are all the same. It's a matter of
which ones pass the 20 MHz test. Marking those that don't as 4 MHz parts
creates income out of what would have been scrap. If they get the process
down so that they ALL pass the 20 MHz test, they could introduce a 40 MHz
part (at higher price) and sell the ones that fail as 20 MHz parts.
       Depending on demand balance between 20 MHz and 4 MHz parts, they may end
up marking some 20 MHz parts as 4 MHz, but you'll never know which ones
those are, so you can't use them in production.
       I remember when Signetics first introduced the NE5534 and the NE5534A
op-amp. I believe they were the same chip, but the A had lower noise.
Again, this was just handled by chip sorting. Sell you best ones for
more!

Harold


FCC Rules Online at http://hallikainen.com/FccRules
Lighting control for theatre and television at http://www.dovesystems.com

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
dl.http://www.juno.com/get/tagj.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
use RemoveMElistservspamTakeThisOuTmitvma.mit.edu?body=SET%20PICList%20DIGEST




2000\11\07@041354 by staff

flavicon
face
Bob Ammerman wrote:
{Quote hidden}

I think there is a lot of truth in that, we bulk buy 16F84 PICs,
and the 16F84A -20P is cheaper now than the -4P or -10P believe
it or not. Something to do with the new factory making them.

What's the bet that they are all -20P now anyway, just re-labeled
as -4P etc to suit orders from older customers. Doesn't matter
a pinch to me, we only buy the 20's as they are the cheapest anyway!
:o)
-Roman

--
http://www.piclist.com hint: To leave the PICList
piclist-unsubscribe-requestEraseMEspam.....mitvma.mit.edu




2000\11\07@042851 by Alan B. Pearce

face picon face
>Understand, I do believe that they would like to produce only 20 MHz parts
>(or whatever the highest speed is) but based on many converations with many
>vendors, I don't think that they are actually able to pull this off.

This is probably the crux of the matter. The costs involved with testing all
parts at maximum speed would be horrible. It may even be that batch testing can
simplify testing at lower speeds, i.e. by batch testing at temperature limits at
20Mhz they may be able to show that room temperature testing at 4Mhz guarantees
full temperature operation at 4Mhz, i.e. 4Mhz parts do not actually get tested
at full temperature range. This makes testing parts at 4Mhz a lot cheaper, and
as many people do not need the higher speed the costs drop dramatically. If you
do need the higher speed then you pay the testing costs to guarantee the full
temp specs at that speed.

If this is not the case, why do Intel provide so many speed variations of the
Pentium when the steps in speed are such small percentages of the operating
frequency?

--
http://www.piclist.com hint: To leave the PICList
EraseMEpiclist-unsubscribe-requestspammitvma.mit.edu




2000\11\07@090602 by Olin Lathrop

flavicon
face
> Which still leaves us here: If the chip says 4 MHz, it may die in strange
> and unexpected ways, at anything higher than 4 MHz.
>
> I wish someone from uChip would step in and make a definitive statement..

They have.  Read the data sheet.  4MHz parts are guaranteed to run up to
4MHz over the full range of the other parameters.  20MHz parts are
guaranteed to run up to 20MHz over the full range of the other parameters.
If you violate any of the specs, whether clock speed or something else,
there is no guarantee that the part will function as described.

For some reason a few "I'll spend a fortune to get something for nothing"
types on this list are questioning what they can get away with on the speed
spec.  The official answer has been and I'm sure will continue to be
"nothing".  I can't quite figure out what part of "nothing" they don't
understand.


*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, RemoveMEolinEraseMEspamEraseMEcognivis.com, http://www.cognivis.com

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestspam_OUTspamKILLspammitvma.mit.edu




2000\11\07@092253 by staff

flavicon
face
Olin Lathrop wrote:
>
> > Which still leaves us here: If the chip says 4 MHz, it may die in strange
> > and unexpected ways, at anything higher than 4 MHz.
> >
> > I wish someone from uChip would step in and make a definitive statement..
>
> They have.  Read the data sheet.  4MHz parts are guaranteed to run up to
> 4MHz over the full range of the other parameters.  20MHz parts are
> guaranteed to run up to 20MHz over the full range of the other parameters.
> If you violate any of the specs, whether clock speed or something else,
> there is no guarantee that the part will function as described.
>
> For some reason a few "I'll spend a fortune to get something for nothing"
> types on this list are questioning what they can get away with on the speed
> spec.  The official answer has been and I'm sure will continue to be
> "nothing".  I can't quite figure out what part of "nothing" they don't
> understand.

<soapbox>
Man you can be hard-headed. I asked a question and many of the posts
were in response. For the record Olin, we only buy 20MHZ PICs, and
run them at much less, AND lately they are CHEAPER than the -4P and
-10P parts anyway!! At least in Australia.

I don't think anyone in this recent thread wanted to get "something
for nothing". I wanted to KNOW what I got, nothing more. I like to
KNOW.

Now the main train of thought seems to be that the good chips pass
ALL tests and are marked 20MHz. The "crappy chips" that fail in one
way or other are marked at the lower rating... So know I want to
KNOW what fails in the "crappy chips". ie, exactly what sort of
failure occurs and at what freq, this is the sort of thing a
good engineer likes to KNOW. I am also curious if the "crappy
chips" may have possibility of other failure, or a higher
probability of failure at normal low-freq operation. Makes sense,
if that die batch has already some proven failure record...

Information like that might be of some use Olin. I understand
you may be bored with this topic but labelling people as cheap,
unprofessional "types" is just insulting with no benefit to
anyone.
</soapbox>
:o) (because roman is always happy)
-Roman

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestTakeThisOuTspamspammitvma.mit.edu




2000\11\08@012142 by w. v. ooijen / f. hanneman

picon face
> > I wish someone from uChip would step in and make a definitive
statement..

> I can't quite figure out what part of "nothing" they don'T  understand.

I don't understand the fuss. It is so simple, and there is something for
both:

1. For guaranteed functionality (which is what you want for a product) use
your chips within specs, and that definitely includes the clock frequency.
That is what uChip promises. period!

2. For adventure (which you might want for hobby, out of plain interest or
for lack of available high-speed chips) use active cooling, very stable
power, a very clean clock, invent your own test suite, and see how far you
can go. YMMV but it can surely be interesting.

Wouter

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\11\08@101625 by Don Hyde

flavicon
face
Remember, the spec sheet is really a contract (that's why you sometimes see
legal weasle-words about medical and life-support stuff at the bottom of
them).  Microchip (or whoever) is guaranteeing that the part will do at
least what it says in the spec sheet.  That means that if you design
something that is within the specs, the supplier is assuming (some of) the
risks if it doesn't work, and they are obligated to help you get it to work
(though that obligation can sometimes be hard to collect on).

You can use the parts outside of the specs, and sometimes get some
spectacular results.  A Microchip FAE told me about customers who were
clocking PIC's at over 50 MHz, and others who were putting them down a
borehole at something like 200C.  When you do, YOU assume all the risks if
it doesn't work, and YOU are responsible for any extra testing and screening
it takes to do it.  And, Microchip or whoever has no obligation to help you
out if they change something and your outside-specs application no longer
works (though they might, if you're buying lots of parts, or they find your
application interesting).

You bought 'em.  You can use the parts any way you want.  If you're doing it
as a business, then you have to do all that risk/benefit thinking.

> {Original Message removed}

More... (looser matching)
- Last day of these posts
- In 2000 , 2001 only
- Today
- New search...