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Original question:

DAC1282: DC Output Generation

DAC1282: DC Output

Yannick Christensen
Prodigy 60 points

Part Number: DAC1282

I'm attempting to use the DAC1282 DC output to troubleshoot the ADC1282 and how I'm parsing the data the ADC1282 is outputting.  I have been able to adjust the sine frequency and gain without issue, and I have been able to read the registers from the DAC1282.  However, when I attempt to put it into DC mode by adjusting the Mode bits and the DCG0->DCG2 registers I just get a static output from the DAC, both outputs are sitting at 2.386V (not differentially) no mater what I try to put the DC gain at.  I am using a single ended power analog power supply of 5V and VRef of 5V from the REF5050 chip and a seperate regulator for the supply voltage.  I've tried triggering the sync pin and changing the order that I change the registers and nothing appears to get the DC output to operate correctly.  Any insight would we greatly appreciated.

  • 0
    TI__Mastermind 44760 points

    Hi Yannick,

    Welcome to the TI E2E Forums!

    Would you be able to share your DAC1282 register settings with me? I'll take a look at your configuration to see if I can spot any issues.

    Also when writing to the DAC1282 registers, have you tried reading them back as a sanity check that they are getting programmed as you expect?

  • 0 in reply to Christopher Hall
    Prodigy 60 points

    Hey Chris,

    I have tried reading them back to make sure the registers are actually configuring. I also made sure to read them before and after to ensure that my reading function is working properly.  I am setting registers 0 through 6 as follows: 0x01, 0x00, 0x00, 0x00, 0x3F, 0xFF, and 0xFF.  I'm having the same issue when I try to use the pulse mode, I can see that the device registering a mode change but both outputs have a common static DC output that doesn't change regardless of the register values.  I'll try and attach what I'm seeing on my scope, its hard to see because both-outputs are quite noisy (which I understand is to be expected) and they overlap, almost entirely.  Let me know if you can find anything.

    Sincerely,

    Yannick

  • 0 in reply to Yannick Christensen
    Prodigy 60 points

    Technically Digikey says my part number is DAC1282IPWR, its not the DAC1282A so i'm assuming everything is the same as the standard DAC1282 model but I just figured I'd note it just incase.

  • 0
    Prodigy 60 points

    I believe I found the issue.  I had the byte endianess flipped, instead of 0xFF, 0xFF, 0x3F, I was writing 0x3F, 0xFF, 0xFF which was just outputting a very small DC output.

  • 0 in reply to Yannick Christensen
    TI__Mastermind 44760 points

    Hi Yannick,

    I'm glad to hear you were able to resolve this issue. Thanks for posting your solution!

    Best regards,
    Chris