paralleling SPI ADC's

[Jamie Morken]

Hi,

I'd like to put two ADC's and a DAC on the same SPI bus, all with
200kHz sampling, but I think I may need to use three separate SPI
buses to do this as the SCLK frequencies as specified in the datasheets
I've seen so far are too low. Anyone know of some 12bit or higher SPI
ADC's/DAC's with fast (40MHz+) SCLK frequencies?

cheers,
Jamie

 

[Jamie Morken]

SPI ports are 8-bit !

You need to use 16 bits * 200K = 3.2Mbits/sec
3 devices = 9.6Mhz

Not much margin for errors.

10Mhz SPI ports may not be able to handle it.

Also the sampling isn't spaced evenly, I need to run the samples
close together and then there is sampling deadtime.

I found a 1MSPS 12bit ADC with 20MHz max SCLK:

http://www.national.com/mpf/DC/ADCS7476.html

cheers,
Jamie