Yes, you could run a clock into the RC oscillator and it would allow
you to wake up without the 1024 Tosc. However, we don't recommend it
because there is an internal pulldown transistor that you will have to
override which will burn a lot of unnecessary current and my affect
the long term reliability of the device.
Rgds, Brian. spam_OUTbbolesTakeThisOuT
microchip.com
______________________________ Reply Separator _________________________________
Subject: Re: Newbie Questions
Author: John Payson <.....supercatKILLspam@spam@MCS.COM> at Internet_Exchange
Date: 10/27/95 4:19 PM
> At 11:32 PM 10/26/95 -0500, you wrote:
[supercat]
> >Is it possible, when using an external oscillator, to have the chip wake
> >instantly from sleep mode (if the oscillator is running?) Normally the
> >16c5x and 16cxx have an oscillator startup timer except in the RC mode.
> >Can the RC mode by made to accept an external oscillator signal (via some
> >suitable resistor or capacitive coupling perhaps?)
[hobbes]
{Quote hidden}> Here is the deal, as far as I can tell. In RC mode you will always have a
> 72ms power-up. In all others you can have either '1024 osc cycles' or '72ms
> + 1024 osc cycles'. This is in all the 'xx data sheets, pg 16 of the '84
> data sheet.
>
> PWRTE=1 PWRTE=0
> ---------------------------------------
> xt,hs,lp | 72ms + | 1024 tosc
> | 1024 tosc |
> ---------------------------------------
> rc | 72ms |
> ---------------------------------------
Right, for powerup those timings apply. For a reset from sleep, however,
only the 1024tosc [if XT, HS, or LP] is applied [nothing at all if RC]. My
question is whether it's possible to use the RC mode with an external osc-
illator so as to dispense with the extra 1024tosc.
