John Luciani wrote:
On 12/11/06, Peter TB Brett <[EMAIL PROTECTED]> wrote:
Also... can anyone suggest a good way to build a square-wave clock
generator
that can vary from 4kHz to 4MHz with a minimum of fuss and a decent
mark-space ratio? I've been scratching my head about this for a
couple of
days, and I still don't have a decent solution...
Have you looked at a PLL with a divide-by-N counter in the feedback loop?
I believe the part that I used was a Motorola MC145151 (this was a few
years back).
I believe the Motorola PLL parts are now sold by Freescale. If you can't
find
them at Freescale try On-Semi.
If it were me and I were using a PLL for this I'd probably be more
inclined to build a 4-8 MHz synthesizer followed by a divide by
2/4/8/.... block. That gives a nicer range for the PLL and a nice 50%
duty cycle. But there are certainly many ways of doing this. You
didn't really mention how accurate it needs to be (must it be based on a
crystal?), required resolution or if it needs to be under digital
control, or the required jitter.
-Dan
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