For the design of the very fast data acquisition system with the ITC232-A, 
a fast 8 bit A/D convertor for consideration is the Analog Devices AD7821.  
It has a fast conversion time and operates from a single +5V supply 
or a +5V and -5V supply.  It will reliably sample at a 1 MHz sample rate.

For anti-aliasing filtering requirements, a quad 2nd order continuous time analog 
filter called the MAX274 is selected.  This continuous time filter solution was 
selected over a switched capacitor solution since clock noise is not a problem, 
the number of sampling rates required are small, operation from a single voltage supply, and cost effectiveness.

Here is a proposed range of sampling frequencies, 
the filter cutoff frequencies, 
and the amount of  time that a sample can be stored in 2 Kb of RAM.
 

Sampling Frequency			Cutoff Frequency		Time (2Kb)
	1 MHz				100 KHz				2 ms
	100 KHz				 10 KHz				20 ms
	10 KHz				  1 KHz				200 ms
	1 KHz				100 Hz				2 s


The quantity, parts numbers and approximate costs for quantity of one part are as follows:

1	AD7821		 20.00
1	MAX274		 14.07
2	74HC393		   .25
1	74HC151		   .37
2	74HC4066	   .56
1	2016 RAM	 10.00   ?
1	74HC126		   .37
1	74HC00		   .37
1	1MHz oscillator	  5.00

	               ~ 50.00


Please send a fax or call me if this is acceptable.

Fred Schuld
