early SuperPROs and RTC

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We were actually the ones to discover the problem with the LPC17xx RTC
oscillator, now as reported in the NXP errata.

http://www.nxp.com/documents/errata_she ... PC1756.pdf

Its what's been holding up production of the SuperPRO.

After 3 re-layouts of the artwork, numerous experiments with cap values and
attempts to test the RTC prior to shipping, just to have it fail later. I just
have to come to the conclusion the present RTC is flaky and it won't be fixed
until NXP has a new revision of the chip.

So SuperPROs will begin shipping in a week, it just won't have a reliable RTC.

[YahooArchive]

I did wonder if the errata was related to the problem you previously reported.

> After 3 re-layouts of the artwork, numerous experiments with cap values and
attempts to test the RTC prior to shipping, just to have it fail later.

Ouch!

> I just have to come to the conclusion the present RTC is flaky and it won't be
fixed until NXP has a new revision of the chip.
>
> So SuperPROs will begin shipping in a week, it just won't have a reliable RTC.
>

There was a discussion started a few weeks ago in the LPC2000 Yahoo groups
regarding this problem.

http://tech.groups.yahoo.com/group/lpc2 ... sage/50376

FYI, one message there states:


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.


Regards,
Chris Burrows

CFB Software
Astrobe: LPC2xxx Oberon-07 Development System
http://www.astrobe.com

[YahooArchive]

This is no longer an issue, all the early units were sold off on eBay with that limitation spelled out.

The RTC works reliably, though it does have a slow startup time (maybe as much as 1 second)