Lpc2000

Very good points, guess I will have to check this one out myself and
as you said wait for the Um that includes the PLCC44 description.

Bob

--- In lpc2000@yahoogroups.com, "unity0724" <unity0724@...> wrote:
>
> Hi, Thanks to your reply.
> 
> From Post/Message #9400:
> Quote: {{We combined the pins VBAT and V18 and made it just a V18. 
> This limits the ability to buffer the RealTimeClock with a battery
> but if the device is in power down mode with V18 applied, the RTC
> will keep running and the RAM contents remains. Current in power
> down is expected typically in the 10 uAs range. }}
> 
> => My interpretation is different, I think they are using same
> LPC2103 silicon and only bond both the VBat and V18 pads together to
> single pin and bring out as single V18. The RTC is tested to run at
> voltage of 1.8V on PLCC44. We are still able to backup the RTC+RAM
> provided the backup supply is regulated at 1.8V (using some
> micropower 1.8V LDO). 
> 
> Shorting of VBat to V18 on LQFP48 could save me lots of trouble.
> Look like we could only figure out what's happening when PLCC44 user 
> manual ready.  :)
> 
> Regards
> 
> --- In lpc2000@yahoogroups.com, "lpc2100_fan" <lpc2100_fan@> 
> wrote:
> >
> > Hi,
> > 
> > if you don't want to use a battery backup, you can leave Vbat open
> > but don't short it to V18. 
> > IMHO the PLCC44 does not connect the second V18, next to Vbat at
> > all.
> > It can not be connected to Vbat internally because this would cause
> > V18 to go up to 3.6V with a new battery. 
> > 
> > Bob
> > 
> > --- In lpc2000@yahoogroups.com, "unity0724" <unity0724@> wrote:
> > >
> > > Hi,
> > > On LPC2103, Can I short VBat to V18?
> > > The 2 pins are next to each other.
> > > => Simplify my PCB layout
> > > => Simplify my RTC backup circuit also, if V18 does not take too
> > >    much current when power down. Single micropower 1.8V LDO used.
> > > 
> > > Vbat requires 3.3V for normal Operation. 
> > > I do not fully understand the datasheet, does VBat work from 
> 2.0V to
> > > 3.6V any time from chip operation to battery backup mode?
> > > On PLCC44, It seems like VBat and V18 are bonded to same pin 
> (read
> > > from previous post) ??
> > > 
> > > I'm not using the full RTC section at the moment, may be will be 
> > > just using the RTC's second tick interrupt as 1mS interval timer 
> > > (Re-program prescaler to very fast "1 second").
> > > 
> > > Thanks
> > >
> >
>