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Original question:

DAC7718: Time to write each channel of the DAC7718

DAC7718: DAC value challenge

Neel Shah101618
Intellectual 550 points
Part Number: DAC7718

Dear DAC team,

We are using the DAC7718 and it looks like the voltage values that we are sending work fine until we send values above 10VDC.

If we end up sending any voltage below 10VDC then the value is considered to be 10VDC only.

Can you advice on what we might be missing here?

Thanks

Ambimat

  • 0
    TI__Mastermind 19086 points

    Hi,

    I didn't understand your question completely. Can you explain it bit more? Is it like whenever you are sending DAC code corresponding to below 10V, you are getting 10V as output?

    Please share your schematics.

    Regards,

    AK

  • 0 in reply to Akhilesh K
    Intellectual 550 points

    Hi Akhilesh,

    The behavior seems to be extremely random actually.

    We are not getting the results reliably back from the DAC. At times when we feed it a voltage of <10VDC we get the values correctly (as has been fed) but at times it happens that any value given that is less than 10VDC the value showing up at the analog end of the DAC is always 10VDC or 10.xx VDC (xx is a two digit decimal value)

    Can you suggest what we might be missing?

    Ambimat Team.

  • 0 in reply to Neel Shah101618
    Intellectual 550 points

    Hi Akhilesh,

    While we continue to test the code we are still not able to get any values below 10VDC on the DAC irrespective of what we enter as the input values.

    Below is a table we created to simulated 240 values going to the DAC where the columns show the individual DAC channels of a single DAC7718.

    We did a simple math where if the value of the channel is x then we are sending the value V = (x/30)*4096. The output will be a number which is approximated to the nearest decimal value, converted to the equivalent hex value and then sent to the DAC. The output is still NOT going below 10VDC (which means the data from the first 4 rows all show as 10VDC (or some additional decimal place) only).

    Can you please guide us?

    Ambimat.

  • 0 in reply to Neel Shah101618
    TI__Mastermind 19086 points

    Hi Neel,

    I am closing this thread, since we have taken this discussion offline

    Regards,

    AK