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AD5313R spi programming problem

Question asked by pmarshall on Oct 28, 2015
Latest reply on Apr 11, 2017 by msamera

I am testing a board that has a AD5313R DAC by bit banging the SPI signals.  I have LDAC and Gain tied to ground.  I am clocking the part at about 200 Hz (very low speed).  My problem is that occasionally when I set a value the output will go to zero or the output will turn off.  I can consistently program the DACB to 32 dec and then program it to 64 dec and the DACB output will turn off.  If I send a command to turn DACB on it has the correct output voltage for value of 64 dec.

 

I have a logic analyzer on the SPI bus and it does not show any issues.  Except when this happens the output voltages I program are correct.  I have some similar issues when programming DACA but I have repeated the above sequence many times.

 

I am using command 3 (Write to and update DAC Channel n) to program the DACs.

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