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Discussion Groups | LPC900 | lpc935 12MHz or 18MHz

Find help, specifications and source code for the LPC900. The LPC900 challenges Microchip and AVR based on the worlds most popular 8-bit architecture the 80C51. With a 2-clock core the LPC900 series is a high performance, very flexible and low cost 8-bit microcontroller family. Designers using or interested in these devices are encouraged to share their know-how and ask questions.

lpc935 12MHz or 18MHz - n172tj - Jan 24 21:29:00 2005


Dear philips_apps monitoring,
conflicting numbers in docs:
in Rev5 Product Data Sheet
2.2 Additional features, middle of page
"Oscillator options support frequencies from
20 kHz to the maximum operating frequency of 18 MHz."
but Ordering Options list
"0 MHz to 12 MHz"
may i or may i not connect 18MHz crystal?
joseph tapay





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Re: lpc935 12MHz or 18MHz - philips_apps - Jan 25 18:19:00 2005


Hello Joseph,

you can connect 18 MHz. The ordering options still need to be update.
We revised the specification from 12 MHz up to 18 after we completed
characterization for all (except the very first LPC932) devices and
seeing that all could run 18 MHz if Vdd is minimum of 3V.

The restrictions for running 18 MHz e.g. that you can not use the
brown out detect have to be considered because the brown out will let
you operate to about 2.6V and this could result in functional failures
below 3V. At 12 MHz the device works 2.4V-3.6V for 18 MHz only 3.0V to
3.6V

Hope this helps,

Philips Apps team --- In lpc900_users@lpc9..., "n172tj" <joseph@t...> wrote:
>
> Dear philips_apps monitoring,
> conflicting numbers in docs:
> in Rev5 Product Data Sheet
> 2.2 Additional features, middle of page
> "Oscillator options support frequencies from
> 20 kHz to the maximum operating frequency of 18 MHz."
> but Ordering Options list
> "0 MHz to 12 MHz"
> may i or may i not connect 18MHz crystal?
> joseph tapay





(You need to be a member of LPC900_users -- send a blank email to LPC900_users-subscribe@yahoogroups.com )

Re: lpc935 12MHz or 18MHz - n172tj - Jan 26 11:49:00 2005


--- In lpc900_users@lpc9..., "philips_apps"
<philips_apps@y...> wrote:
> you can connect 18 MHz.

Philips Apps Team, you rock...
thanks for the info not available from data sheets. It is great help
to us
to plan ahead. I already know several applications for 18Mhz
LPC9xxx...
With your support LPC9xxx is becoming my favorite chip and I am not
easy...

Would you please help with assembly source code (table driven and
otherwise)
for crc-32 calculation to
match chip's returning crc32 with precalculated values. This must be
a great
interest of all developers to verify chip's integrity during chip's
lifetime, after flash writes, etc.
How is the CRC32 generated on the chip? Is it hardwired logic or
software?
thanks again
joseph tapay



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