CCS/DAC8775: DAC8775 does not work properly? SPI communication failed!!!

The SPI timing of sending configuration parameters is shown in the figure：

The SPI timing sequence of reading register data is shown in the figure. But no feedback data has been received.

I make sure all the circuits and voltages are in order. It's an emergency, but There was nothing I could do.

Hello

I took a look at the schematic and for the most part is looks okay. However, you should replace the CCOMP capacitors with 150pF instead of 0.1nF. That however should not affect the SPI.

Can you first confirm that the device powers up correctly? What is the measured current on 'DAC_12V' at power up? Can you also measure and report DVDD and DAC_VPOS_IN_A voltages at power up?  These measurements can be used to confirm the correct power up of the device. Below are the expected measurements.

DAC_12V current: 3-6 mA

DVDD: 5V

DAC_VPOS_IN_A: 3.4V

If those measurements are confirmed, can you try writing and reading back any of the SPI registers to confirm your SPI frame is correct? You can attempt to enable the internal reference and measure it by writing to '1' to bit 4, addr 0x02. 

If that works, then proceed to configure and enable the buckboost converters, then the DAC, before attempting to set the DAC output current. 

Let me know if this works for you.

Regards

Reza

Hello, 

Can you also re-attached you SPI timing diagrams so I can review? For some reason I do not see the images you attached in your earlier post. 

Thanks,

Reza

Hello,

I am also working with DAC8775, and I would like to see your configuration, but unfortunately, the images are not shown. Could you please reload them?

Thank you!

Tatiana

Thanks. Can you re upload your images for Tatiana to leverage as well? Also, can you close this thread once your done with that? I appreciate it and do let me know if you have any other issues.

Regards

Reza