Lpc2000

Hi Guys,

We have built a few  boards with LPC2104's and 1 or 2 are not 
powering up and are hanging after power up.

We scope the 1.8v and 3.3v and the waveforms seem to be consistently 
power fast and together.

has any on had power up problems on the 2104?

Is there anything to watch for? as there are no power up timing 
diagrams in the data sheets for 1.8v and 3.3v.

Could it be something else? PLL  Xtal?  Glitches in to the IO?

a reset seems to kick it in to life.

Any other pointers would be appreciated.

TIA  (Thanks in advance)
Frank

At 11:58 AM 12/8/05 +0000, phlpcmicro wrote:
>We have built a few  boards with LPC2104's and 1 or 2 are not
>powering up and are hanging after power up.

How so?  Do they just never start? Can you perform an ISP operation on them>

>We scope the 1.8v and 3.3v and the waveforms seem to be consistently
>power fast and together.


Within reason there don't appear to be any power sequencing issues on these 
micros.

>has any on had power up problems on the 2104?
>
>Is there anything to watch for? as there are no power up timing
>diagrams in the data sheets for 1.8v and 3.3v.

The biggest thing to watch for is have you inadvertently put the processor 
in ISP mode by having the ISP pin low on reset?

>Could it be something else? PLL  Xtal?  Glitches in to the IO?
>
>a reset seems to kick it in to life.


That might suggest a low rise on the ISP pin or a bad power-on reset 
circuit.  You do use a 'real' power on reset circuit?

Robert

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