Lpc2000

We're working with several prototype boards.  Because of a layout error,
we have a jumper on the linear regulator circuit.  On 2 boards, the
jumper broke free and 1.8V was driven to the LPC2106 without 3.3V.  On
one of these board, the LPC2106 seems to have died (no oscillation); on
the other, it's still working.

My question: does supplying 1.8V to an LPC2106 without 3.3V damage or
destroy the part?  We're trying to figure out whether we need to replace
the LPC2106 on the second board.

Thanks.

--- In lpc2000@yahoogroups.com, "James Dabbs" <jdabbs@t...> wrote:
> We're working with several prototype boards.  Because of a layout 
error,
> we have a jumper on the linear regulator circuit.  On 2 boards, the
> jumper broke free and 1.8V was driven to the LPC2106 without 3.3V.  
On
> one of these board, the LPC2106 seems to have died (no 
oscillation); on
> the other, it's still working.
> 
> My question: does supplying 1.8V to an LPC2106 without 3.3V damage 
or
> destroy the part?  We're trying to figure out whether we need to 
replace
> the LPC2106 on the second board.

Just guessing - CMOS can do funny things sometimes like going into 
a 'latch-up' state, drawing lots of current and getting very hot. 
This can damage the chip if the power isn't disconnected. With the 
3.3V disconnected this might have happened. The other chip is 
probably OK.

Leon

--- In lpc2000@yahoogroups.com, "leon_heller" <leon_heller@h...> 
wrote:
> --- In lpc2000@yahoogroups.com, "James Dabbs" <jdabbs@t...> wrote:
> > We're working with several prototype boards.  Because of a 
layout 
> error,
> > we have a jumper on the linear regulator circuit.  On 2 boards, 
the
> > jumper broke free and 1.8V was driven to the LPC2106 without 
3.3V.  
> On
> > one of these board, the LPC2106 seems to have died (no 
> oscillation); on
> > the other, it's still working.
> > 
> > My question: does supplying 1.8V to an LPC2106 without 3.3V 
damage 
> or
> > destroy the part?  We're trying to figure out whether we need to 
> replace
> > the LPC2106 on the second board.
> 
> Just guessing - CMOS can do funny things sometimes like going into 
> a 'latch-up' state, drawing lots of current and getting very hot. 
> This can damage the chip if the power isn't disconnected. With the 
> 3.3V disconnected this might have happened. 
On the other hand I've deliberately powered up a 2104 with no 3.3V 
supply with no noticeable effect.  That combined with Philips 
statements that there are no sequencing issues would lead me to 
believe that it isn't particulary vulnerable to CMOS latchup.

Robert