NEIL B. GANDLER <V064MB9K@UBVMS.CC.BUFFALO.EDU> wrote:

>Is it always necessary for an RC circuit on the MCLR' pin
>during power up? In the PIC Microntoller book, pages 2-39,
>they recommend such a circuit for slow power up conditions.
>Would a circuit running off a 9V battery through a low
>dropout regulator be considered a slow VDD power up? They
>don't seem to give any numeric specs.

Neil:

They DO give numeric specs; "slow" is defined as anything slower than
0.05V/ms (16C5x data sheet, section 7.4.1).  However, this spec assumes
that power-up is monotonic and starts at 0V. Since you can't guarantee
these conditions when plugging in your 9V battery, you should put an RC
on the MCLR line.

-Andy

--
Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California