In article <4aps73$> LEFRAK-B-25@ writes:
>From: LEFRAK-B-25@
>Subject: Simple Crystal and Clock Qustions
>Date: 14 Dec 1995 18:59:47 GMT

>I am trying to use a National Semiconductor ADC1038 A/D converter.  I want to
>attach an external clock to the Cclk input.  My question is how do I hook up a 
>simple crystal to this input.  If this is trivial please forgive me, I am just a
>hobbyist...Below is my plan is it right, kinda right or WRONG...

>I got a CY3.57Mhz crystal.  I will take two 15pf caps and place them between
>ground and each lead of the cystal.  I will also place a 1Meg resistor between
>each lead of crystal.
>Now I take one side of the crystal and put it into a CMOS inverter.  I take the
>output of this inverter and tie it together with the other side of the crystal
>and then put both through another inverter.  
>I think I can then take the output of the second inverter and put it into the
>Cclk input. 

>Any help would be greatly appreciated...


14 MHz clock:

Aa you pointed out correctly, a crystal must be used with some active elements 
to function as an oscillator; a complete schematic:

       |\             |\               _   _
   ----|  >o----------|  >o----> out _| |_| |_ 3.57MHz
  |    |/       |     |/
  |     ___     |
  |      1M     |
  |            | |
  |      _     | |1K5
  |     | |     |
  |----|| ||----|
  |     |_|     |
  |  crystal    |
 ---           ---
 --- 33pF      --- 18pF
  |             |
 ___           ___
 ///           ///

The 1K5 resistor limits the power dissipated in the crystal. 
So your plan was (almost completely) correct.



 Richard Rasker
 Calslaan 54-11
 7522 MG  Enschede

Date: Sun, 17 Dec 1995 22:21:49 UNDEFINED

Original Subject: Re: Simple Crystal and Clock Qustions

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