problem with the continous mode of AD7738

Question

I cannot read the status and data registers in the continuous mode of AD7738. The single mode is OK. On page 23 of the data sheet in fig.12 the value of the mode register for the continuous mode is wrong. Couldn't find errata for the AD7738.Any idea?

ADIApproved · Accepted Answer

Hi Peter, 
 As I was looking at your scope shots, I saw that the DIN went high for more than 100ns and that might have caused your device to exit the continuous read mode. I've pointed that in the attached pic. 
 The part enters continuous read mode after the last rising edge of SCLK when writing 48h. Bringing DIN high after this write would exit the continuous read mode. DIN must be kept low after the write of 48h to keep it in continuous read mode. 
 I have attached scope shots of a working set-up using one of our Evaluation Boards for AD7738. 
 As you can see, DIN is always kept low so that a write to the part can be avoided while it is reading. Also, this would keep it into continuous read mode as the DIN is never brought high for 100ns. 
 I hope this helps. 
 Thanks and Best Regards, 
 Chris)

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problem with the continous mode of AD7738