AD5686R Output voltages are not as expected

HI, 

What SPI Mode are you using? I believe it should be SPI Mode 1 or 2 for the AD5686R. Also, check your logic levels vs the logic supply on the chip. An SCLK, MOSI, and SYNC osc capture on the failing values would be best.

Regards,

~Ian

Hi Ian,

we have tried on SPI Mode 0,1 and 2.

Above is the oscilloscope data, for the data 0x6FFF, DAC output voltage suppose to be 1.094, but output voltage is zero. please 0x7FFF DAC out voltage is as expected.

Above oscilloscope data has

Command: WRITE_AND_UPDATE_CMD (0x3)

Address: DAC_A (0x1)

Data: 0x6FFF

Could you please suggest, what might be going wrong?

Hi, 

Sorry, I didn't see the /SYNC signal on your scope shot. What I'm seeing now is that there are more than 24 clocks on the bus, and apologies as I don't have an eval board on hand, but I'm not sure it would create a valid response from the DAC in this case. 

Could you try to get the /SYNC waveform and send only 24bits word to the DAC? SPI Mode 1 or 2 should work, with the data valid at the CLK falling edge. 

Regards,

Ian

Hi, 

Sorry, I didn't see the /SYNC signal on your scope shot. What I'm seeing now is that there are more than 24 clocks on the bus, and apologies as I don't have an eval board on hand, but I'm not sure it would create a valid response from the DAC in this case. 

Could you try to get the /SYNC waveform and send only 24bits word to the DAC? SPI Mode 1 or 2 should work, with the data valid at the CLK falling edge. 

Regards,

Ian

Hi AnkalG , 

Is the problem solved on your end?

Yes. Issue got resolved.

Problem was with sync signal was going high for every byte, that was causing problem.