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AD7607 No MISO output

Hello , 

I am currently using AD7607 to read analog signal in the range of -+10V , I am interfacing the said IC with SOM , The SPI signal coming from SOM are isolated using ADuM262N1BRIZ. Now the problem is I am able to get busy signal i am also getting 2.5V reference voltage, but i am not getting MISO output of ADC . Please find the schematic attached. 

Following are configuration 

R47 DNP i.e HBEN 

R80= GND using 0E resistor i.e DB15

Reset pull down using 1K resistor 

OS[0:2] =000

REF Select = logic 1 , internal reference ( we are getting 2.5V ) 

Pin 25 floating 

Please help . When first batch was manufacture the same sch was working , now in second batch we are getting multiple failure . 

is there any fundamental flaw in the schematic ? 

Please help me here we are in production phase . We have already manufacture ~2K PCB in batch of 10 . In first batch we did not got such issue , now in second batch we are facing no MISO . 

We have also probed the pin the DoutA pin randomly goes high for 10uS & stays low. 

Prompt reply will be appreciated . 

Gaurav 

Pin 24 used as MISO PDF

 

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  • Hi Gaurav,

    That's difficult to support if with the same schematic, some batches work and some doesn't. Schematic looks correct. Can you do the exercise of swapping the IC from a good board and a bad board?

    For debugging, I'd suggest checking the PAR/SER pin, RESET pin, or scope the CS with SCLK together.

    Regards,

    Lluis.

Reply
  • Hi Gaurav,

    That's difficult to support if with the same schematic, some batches work and some doesn't. Schematic looks correct. Can you do the exercise of swapping the IC from a good board and a bad board?

    For debugging, I'd suggest checking the PAR/SER pin, RESET pin, or scope the CS with SCLK together.

    Regards,

    Lluis.

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