AD7656 Analog Digital Converter

Hi everyone,

I'm trying to use AD7656 for Analog conversion, controlled by a microcontroller. I have used the circuit recommended on page 22 of the datasheet for a parallel conversion with external reference, but it doesn't work. I checked the different inputs, CS et RD and CONVABC (they are all used together) and they are like indicated by datasheet. On the other hand, signal BUSY doesn't appear at all and there is no digital output at all. Do you hqve any idea where my problem could be?

I would be very thankful if you can help me to solve this problem.

Best Regards,


  • HI Baldiri,

         Can you verify the correct voltage is applied to all the hardware control pins.

    Did you give the part a reset after power up?

    Can you see the 2.5V on the REFCAP A,B,C pins?

    Is pin 63 set to a logic low?

    The AD7656 should see a valid CONVST pulse, after the reset signal, in order to perform a valid conversion.

    If you want to share your schematics it may help to identify the problem.



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