To me NXP gave this explanation:
The problem is it does not work at extreme temperatures. At room temperature it has an asymmetric duty cycle and is more sensitive to the specific crystal used than it should be, so it also may not work. You can probably get it to work for development but it is not dependable enough to go into production.
We will have the errata fixed LPC1700 - RTC parts released for sale in the latter half of Q4.
--- In l..., "daniel.widyanto" wrote:
>
> Hi all,
>
> Quote from NXP sources:
> "The fix for the RTC is understood and fixed silicon has taped out. We will have the fixed RTC parts (for LPC17xx) released for sale in the latter half of Q4"
>
> Hope that helps.
>
> Regards,
> -daniel
>
> --- In l..., "Bob T" wrote:
> >
> > Chris,
> > NXP headquarters are in the Netherlands but the microcontrollers are designed and supported from San Jose, CA. In all likelihood this issue is very hot right now in the design team. Analog problems are sometimes extremely difficult to quantify and we could be talking about some nanoamps here and there that determine whether the RTC is reliable or not.
> > Testing is easy for features that are digital and fast but not so easy for analog, slow, leakage dependent, temperature dependent, may be voltage dependent...??
> > I am sure NXP tested at nominal and limit values but not all possible combination thereof. And there is that unknown element of process variation. Even if several manufacturing lots were tested, there is still a potential for failure.
> > Please don't get me wrong, this is not an excuse for missing this errata.
> > There will be a fix, no doubt the question is whether the redesign or your mass production will be sooner.
> > Before abandoning ship and looking at other options, stay calm and give NXP a couple days to react.
> > btw. I am not from NXP or paid by or sponsored by.... NXP.
> >
> > Hope that this will come to a resolution soon.
> >
> > Bob
>

An Engineer's Guide to the LPC2100 Series

--- In l..., "daniel.widyanto" wrote:
>
> Quote from NXP sources:
> "The fix for the RTC is understood and fixed silicon has taped out. We will have the fixed RTC parts (for LPC17xx) released for sale in the latter half of Q4"
>
> Hope that helps.
>

Thanks for the info. Did the NXP source detail what the problem actually is e.g. does the problem only exist for part of the specified temperature range?

Hi all,

Quote from NXP sources:
"The fix for the RTC is understood and fixed silicon has taped out. We will have the fixed RTC parts (for LPC17xx) released for sale in the latter half of Q4"

Hope that helps.

Regards,
-daniel

--- In l..., "Bob T" wrote:
>
> Chris,
> NXP headquarters are in the Netherlands but the microcontrollers are designed and supported from San Jose, CA. In all likelihood this issue is very hot right now in the design team. Analog problems are sometimes extremely difficult to quantify and we could be talking about some nanoamps here and there that determine whether the RTC is reliable or not.
> Testing is easy for features that are digital and fast but not so easy for analog, slow, leakage dependent, temperature dependent, may be voltage dependent...??
> I am sure NXP tested at nominal and limit values but not all possible combination thereof. And there is that unknown element of process variation. Even if several manufacturing lots were tested, there is still a potential for failure.
> Please don't get me wrong, this is not an excuse for missing this errata.
> There will be a fix, no doubt the question is whether the redesign or your mass production will be sooner.
> Before abandoning ship and looking at other options, stay calm and give NXP a couple days to react.
> btw. I am not from NXP or paid by or sponsored by.... NXP.
>
> Hope that this will come to a resolution soon.
>
> Bob

Chris,
NXP headquarters are in the Netherlands but the microcontrollers are designed and supported from San Jose, CA. In all likelihood this issue is very hot right now in the design team. Analog problems are sometimes extremely difficult to quantify and we could be talking about some nanoamps here and there that determine whether the RTC is reliable or not.
Testing is easy for features that are digital and fast but not so easy for analog, slow, leakage dependent, temperature dependent, may be voltage dependent...??
I am sure NXP tested at nominal and limit values but not all possible combination thereof. And there is that unknown element of process variation. Even if several manufacturing lots were tested, there is still a potential for failure.
Please don't get me wrong, this is not an excuse for missing this errata.
There will be a fix, no doubt the question is whether the redesign or your mass production will be sooner.
Before abandoning ship and looking at other options, stay calm and give NXP a couple days to react.
btw. I am not from NXP or paid by or sponsored by.... NXP.

Hope that this will come to a resolution soon.

Bob

--- In l..., "cfbsoftware1" wrote:
>
> --- In l..., Olivier Gautherot wrote:
> >
> > I've snipped all the discussion - Is anyone chasing the actual issue with
> > NXP and will send the reply to the list or is it better to contact tech
> > support individually? I guess that, if we all send reports, they will have
> > more pressure to document more thoroughly the issue and publish some plans
> > :-)
>
> I noticed that the issue has also been raised on the NXP MCU discussion forum:
>
> http://forums.nxp.com/viewforum.php?f=1
>
> However, Europe is on summer holiday right now isn't it ;-)
>
> Regards,
> Chris
>

--- In l..., Olivier Gautherot wrote:
>
> I've snipped all the discussion - Is anyone chasing the actual issue with
> NXP and will send the reply to the list or is it better to contact tech
> support individually? I guess that, if we all send reports, they will have
> more pressure to document more thoroughly the issue and publish some plans
> :-)

I noticed that the issue has also been raised on the NXP MCU discussion forum:

http://forums.nxp.com/viewforum.php?f=1

However, Europe is on summer holiday right now isn't it ;-)

Regards,
Chris

Hi to all and many thanks for the heads-up. I was indeed considering the
LPC1768 for a project that could be running at extreme temperatures
(possibly above +50C from time to time and definitely below -20C in the
winter at some locations).

I've snipped all the discussion - Is anyone chasing the actual issue with
NXP and will send the reply to the list or is it better to contact tech
support individually? I guess that, if we all send reports, they will have
more pressure to document more thoroughly the issue and publish some plans
:-)

Thanks in advance
Cheers
Olivier
On Mon, Jul 26, 2010 at 6:10 PM, Mike Harrison wrote:

> On Tue, 27 Jul 2010 01:22:54 +0530, you wrote:
>
> >1751, 1752, 1754, 1756, 1758, 1759, 1763, 1764, 1765, 1766, 1768, 1769 all
> >have the problem mentioned in their Errata Sheets.
> >
> >1767 does not have an errata doc updated in July 2010 like the others.
> > Either they will update it soon, or it is free of the problem. [...]
>
Olivier Gautherot
o...@gautherot.net
Cel:+56 98 730 9361
www.gautherot.net
http://www.linkedin.com/in/ogautherot

Hi Ahmad,

Your speculation makes sense. I had an 'invisible' problem with the RTC a
few weeks ago, on my first prototype. I am not quite sure of what happened
exactly but everything seems to show that it was dirt on the PCB (flux
residues,etc), that fortunately did not occurred on the production line. So,
the RTC circuitry is really sensible (much more than the LPC23 version and
other chips I used in the past).

More disturbing than the errata itself is the total lack of information
about the problem.

Regards,
Sergio.

On Mon, Jul 26, 2010 at 16:52, Ahmad wrote:

> 1751, 1752, 1754, 1756, 1758, 1759, 1763, 1764, 1765, 1766, 1768, 1769 all
> have the problem mentioned in their Errata Sheets.
>
> 1767 does not have an errata doc updated in July 2010 like the others.
> Either they will update it soon, or it is free of the problem.
>
> I may end up back with the 2365 which is pin compatible... It will mean
> losing out on the advantages that I was counting on in the 17xx family, but
> at least it is a change that requires no PCB revision.
>
> I consider this a HUGE goof-up by NXP.
>
> But here's my speculation about it:
>
> The 17xx series has brought the RTC power consumption down dramatically
> from what it was in the 23xx series. The RTC circuit is therefore
> susceptible to even very small leakage and parasitic currents. These are
> always a function of temperature. Higher temperatures give rise to larger
> leakage currents, which could disturb normal (ideal) operation of the
> transistors. I would therefore think that towards the 70+ degree C mark,
> there may be unreliability. In which case it would be good enough for more
> moderate temperature use. On the other hand, junction voltage drops rise
> with lower temperatures(at least for diodes), so this might also be a
> problem when tuning the chip design for low low power. Also to be
> considered is that the July 2010 edition of the Errata is Revision 4. This
> means that the problem was not noticed or proven for quite a long time
> (since October 2009, a gap of 9 months). I would think it is a very rare
> problem.
>
> I'm hoping NXP tech support will be more specific about the problem. I'm
> not throwing out my 1765 chips yet.
>
> I'm also hoping that a chip revision will be out soon... fingers crossed.
> I would really hate to have to change 10K LOC to have it run on another
> chip.
>
> --Ahmad
>
> On Mon, Jul 26, 2010 at 4:51 PM, John Devereux wrote:
>
>> Pete Vidler > writes:
>>
>> > On 26/07/2010 06:37, afolly_mil2 wrote:
>> >> Problem:
>> > > The RTC does not work reliably within the temperature
>> > specification.
>> > ...
>> >> All I can surmise is that it might not work at temperature extremes,
>> >> but even that is conjecture.
>> >
>> > Yes, that seems to be what they are implying. Without specifics,
>> > which
>> > do not appear to be provided, you simply can't rely on the RTC with
>> > this
>> > chip. That's a serious problem!
>> >
>> > Let us know if you hear back from NXP.
>>
>> What about the other chips in the 17xx family? Are they OK? We are
>> looking at switching but absolutely need the RTC to work!
>>
>> --
>>
>> John Devereux
>
>

On Tue, 27 Jul 2010 01:22:54 +0530, you wrote:

>1751, 1752, 1754, 1756, 1758, 1759, 1763, 1764, 1765, 1766, 1768, 1769 all
>have the problem mentioned in their Errata Sheets.
>
>1767 does not have an errata doc updated in July 2010 like the others.
> Either they will update it soon, or it is free of the problem.
>
>I may end up back with the 2365 which is pin compatible... It will mean
>losing out on the advantages that I was counting on in the 17xx family, but
>at least it is a change that requires no PCB revision.
>
>I consider this a HUGE goof-up by NXP.
>
>But here's my speculation about it:
>
>The 17xx series has brought the RTC power consumption down dramatically from
>what it was in the 23xx series. The RTC circuit is therefore susceptible to
>even very small leakage and parasitic currents. These are always a function
>of temperature. Higher temperatures give rise to larger leakage currents,
>which could disturb normal (ideal) operation of the transistors. I would
>therefore think that towards the 70+ degree C mark, there may be
>unreliability. In which case it would be good enough for more moderate
>temperature use. On the other hand, junction voltage drops rise with lower
>temperatures(at least for diodes), so this might also be a problem when
>tuning the chip design for low low power. Also to be considered is that the
>July 2010 edition of the Errata is Revision 4. This means that the problem
>was not noticed or proven for quite a long time (since October 2009, a gap
>of 9 months). I would think it is a very rare problem.

..or a problem that only occurs on some production silicon.

1751, 1752, 1754, 1756, 1758, 1759, 1763, 1764, 1765, 1766, 1768, 1769 all
have the problem mentioned in their Errata Sheets.

1767 does not have an errata doc updated in July 2010 like the others.
Either they will update it soon, or it is free of the problem.

I may end up back with the 2365 which is pin compatible... It will mean
losing out on the advantages that I was counting on in the 17xx family, but
at least it is a change that requires no PCB revision.

I consider this a HUGE goof-up by NXP.

But here's my speculation about it:

The 17xx series has brought the RTC power consumption down dramatically from
what it was in the 23xx series. The RTC circuit is therefore susceptible to
even very small leakage and parasitic currents. These are always a function
of temperature. Higher temperatures give rise to larger leakage currents,
which could disturb normal (ideal) operation of the transistors. I would
therefore think that towards the 70+ degree C mark, there may be
unreliability. In which case it would be good enough for more moderate
temperature use. On the other hand, junction voltage drops rise with lower
temperatures(at least for diodes), so this might also be a problem when
tuning the chip design for low low power. Also to be considered is that the
July 2010 edition of the Errata is Revision 4. This means that the problem
was not noticed or proven for quite a long time (since October 2009, a gap
of 9 months). I would think it is a very rare problem.

I'm hoping NXP tech support will be more specific about the problem. I'm
not throwing out my 1765 chips yet.

I'm also hoping that a chip revision will be out soon... fingers crossed. I
would really hate to have to change 10K LOC to have it run on another chip.

--Ahmad

On Mon, Jul 26, 2010 at 4:51 PM, John Devereux wrote:

> Pete Vidler > writes:
>
> > On 26/07/2010 06:37, afolly_mil2 wrote:
> >> Problem:
> > > The RTC does not work reliably within the temperature
> > specification.
> > ...
> >> All I can surmise is that it might not work at temperature extremes,
> >> but even that is conjecture.
> >
> > Yes, that seems to be what they are implying. Without specifics,
> > which
> > do not appear to be provided, you simply can't rely on the RTC with
> > this
> > chip. That's a serious problem!
> >
> > Let us know if you hear back from NXP.
>
> What about the other chips in the 17xx family? Are they OK? We are
> looking at switching but absolutely need the RTC to work!
>
> --
>
> John Devereux
>
>
>

Pete Vidler writes:

> On 26/07/2010 06:37, afolly_mil2 wrote:
>> Problem:
> > The RTC does not work reliably within the temperature
> specification.
> ...
>> All I can surmise is that it might not work at temperature extremes,
>> but even that is conjecture.
>
> Yes, that seems to be what they are implying. Without specifics,
> which
> do not appear to be provided, you simply can't rely on the RTC with
> this
> chip. That's a serious problem!
>
> Let us know if you hear back from NXP.

What about the other chips in the 17xx family? Are they OK? We are
looking at switching but absolutely need the RTC to work!

--

John Devereux