LTC2400 Intermittent SDO Output

Question

I have a LTC2400 ADC and am attempting to connect it to a TI TM4C1294NCPDT micro-controller. I have configured the micro-controller to use external serial clock, single cycle operation. The ADC is isolated from the micro-controller through a digital isolator.

The SDO output on the ADC is not producing an output that looks correct. This signal is not consistent. 
 
 CH1 => ADC SDO 
 CH2 => CS 
 CH3 => SCLK 
 Any advice would be appreciated.

LoganC · Accepted Answer

Hi allan@overst.net , 
 With F0 tied to GND, each conversion will take a minimum of 130ms. From the scope capture it appears that CSn is only high for about 200us - meaning the conversion hasn't finished. When CSn is pulled low SDO is outputting the EOCn signal - only after EOCn goes low to indicate the conversion has finished should the SCLK begin transitioning to clock out the conversion result. Page 15 of the datasheet gives more information on the external clock, single cycle operation. 
 -Logan

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LTC2400 Intermittent SDO Output

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