On 24 Jul 96 , John B C Walker wrote:

>        John Knechtel said that XT is okay down to 200kHz, but Andrew
>Warren and the Microchip Data Book state a minimum frequency of 1MHz
>for XT (19-2, page 2-998 of 1995-96 book). John, where did the 200kHz
>come from?


My answer came from the (Preliminary) data in 12.3, p2-676 of the
1994 book which has contains a spec of .2-25MHz for XT mode.

Look more carefully at note 1 on p2-998 of the 1995-96 book, it
actually covers your case and says that it should work.

The buffer almost certainly is DC coupled and *ought* to work.

Another ideas/questions:
You are putting your clock into OSC1 I assume... Have you looked at
the quality of the clock coming out of OSC2? That would be the clock
used internally so anything odd showing up there would cause
problems.

Have you tried loading OSC2 with a small C (100pF) load more like it
would be with a crystal circuit there?

Try driving with a slightly reduced amplitude sine. That would be
more like the filtered signal the crystal passes as feedback..

Good luck!
JohnK
--
John Knechtel (knechtel@enchantsoft.com)
Voice (414)426-8372
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