Lpc2000

unity0724 wrote:

>Hi,
>On LPC2103, Can I short VBat to V18?
>  
>
No

>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?
>  
>
The 32KHz oscillator and clock circuitry (counters) operate over the 2.0 
.. 3.6volt range.  This is the typical discharge life of a lithium 
cell.  As the data sheet says: 2.0..3.6v.  If you connect it to 1.8v 
then it is too low a voltage to run the electronics (RTC).


PCB layout can be a PITA, but ....

Regards,

TomW


>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
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>Yahoo! Groups Links
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-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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