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Discussion Groups | LPC900 | Crystal oscillator doesn't work on P89LPC936
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.
Crystal oscillator doesn't work on P89LPC936 - pyalpc936 - Jul 18 4:35:45 2007
Hi,
I'm using a P89LPC936 with a 12MHz crystal (SMD case HC49/4H)
The uC doesn't always start.
It seems that oscillation level is too small (0.5V to 1.6V with 3.3V
Vdd).
Also it seems to work fine with a classic crystal (not SMD).
The reason could be that classic crystal have serie resistance (about
10 ohms) much lower then SMD crystal (about 30 ohms). And the 89LPC936
doesn't have enough gain to compensate the lost due du serial
resistance.
I don't find any information about crystal to use with LPC9XX
microcontroler.
Does anyone have informations or perhaps similar problems ?
Thanks a lot
(You need to be a member of LPC900_users -- send a blank email to LPC900_users-subscribe@yahoogroups.com )
I'm using a P89LPC936 with a 12MHz crystal (SMD case HC49/4H)
The uC doesn't always start.
It seems that oscillation level is too small (0.5V to 1.6V with 3.3V
Vdd).
Also it seems to work fine with a classic crystal (not SMD).
The reason could be that classic crystal have serie resistance (about
10 ohms) much lower then SMD crystal (about 30 ohms). And the 89LPC936
doesn't have enough gain to compensate the lost due du serial
resistance.
I don't find any information about crystal to use with LPC9XX
microcontroler.
Does anyone have informations or perhaps similar problems ?
Thanks a lot
(You need to be a member of LPC900_users -- send a blank email to LPC900_users-subscribe@yahoogroups.com )
Re: Crystal oscillator doesn't work on P89LPC936 - mcu_monkey - Jul 23 17:47:21 2007
Hi,
There seems to be an issue with startup on some types of crystals.
NXP put out an app note:
http://www.standardics.nxp.com/support/documents/microcontrollers/pdf/an10289.pdf
Hope it helps.
Jeff
--- In l...@yahoogroups.com, "pyalpc936" wrote:
>
> Hi,
> I'm using a P89LPC936 with a 12MHz crystal (SMD case HC49/4H)
> The uC doesn't always start.
> It seems that oscillation level is too small (0.5V to 1.6V with 3.3V
> Vdd).
> Also it seems to work fine with a classic crystal (not SMD).
> The reason could be that classic crystal have serie resistance (about
> 10 ohms) much lower then SMD crystal (about 30 ohms). And the 89LPC936
> doesn't have enough gain to compensate the lost due du serial
> resistance.
> I don't find any information about crystal to use with LPC9XX
> microcontroler.
>
> Does anyone have informations or perhaps similar problems ?
>
> Thanks a lot
>
(You need to be a member of LPC900_users -- send a blank email to LPC900_users-subscribe@yahoogroups.com )
There seems to be an issue with startup on some types of crystals.
NXP put out an app note:
http://www.standardics.nxp.com/support/documents/microcontrollers/pdf/an10289.pdf
Hope it helps.
Jeff
--- In l...@yahoogroups.com, "pyalpc936"
>
> Hi,
> I'm using a P89LPC936 with a 12MHz crystal (SMD case HC49/4H)
> The uC doesn't always start.
> It seems that oscillation level is too small (0.5V to 1.6V with 3.3V
> Vdd).
> Also it seems to work fine with a classic crystal (not SMD).
> The reason could be that classic crystal have serie resistance (about
> 10 ohms) much lower then SMD crystal (about 30 ohms). And the 89LPC936
> doesn't have enough gain to compensate the lost due du serial
> resistance.
> I don't find any information about crystal to use with LPC9XX
> microcontroler.
>
> Does anyone have informations or perhaps similar problems ?
>
> Thanks a lot
>
(You need to be a member of LPC900_users -- send a blank email to LPC900_users-subscribe@yahoogroups.com )