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TLC5628

Mike Heim
Prodigy 50 points
Other Parts Discussed in Thread: TLC5628

I think I am having an issue with the logic diagram of how the data is shifted in and out of the DAC.  I am using the Load controlled update method and sending 255 to the DAC so it should report the full reference voltage.  Below is a  'generic' program of what I am telling the DAC to do, can anyone enlighten me as to whether or not I am sending the data incorrectly?

---INITIALIZE---

HIGH LOAD

LOW LDAC

---SENDING DATA---

DO

LOW LOAD         (allows data to be sent from the serial input to the desired DAC?)

HIGH LOAD 

#255 being sent out

LOOP

Any suggestions?

  • 0
    Prodigy 50 points

    Hi,

    Right off the bat, I'm new to all of this so please forgive a stupid question.  I am trying to use the TLC5628 DAC to convert an input signal to an analog voltage for a project.  After reading the data sheet, I thought I had an idea as to how to do this, but something isn't working right.  I correctly selected the channel I wanted to use (A) and am sending digital inputs into the chip, but every output voltage is 1.5 times the input signal.  I'll admit I'm not sure I fully understand the output voltage equation given on page 3 of the data sheet, so I think the is where my issue lies.  Can anyone, please, elaborate on the specific terms for this equation? FYI my ref voltage is 5.0V.  Thank you for the help!

    Mike

  • 0
    TI__Guru**** 168605 points

    Hi Mike,

    Welcome to the forum!  Can you send a screen capture of your SPI transmission to the TLC5628?  Let us know what sort of processor you are talking to the DAC with as well.

  • 0 in reply to Tom Hendrick
    Prodigy 50 points

    Hi Tom,

    Sorry, I should have posted that I have resolved my issue.  I had VREF at the same voltage as I was powering the chip with.  Once I lowered it to being 1.5 V less than the supplied voltage, it worked like a charm!  Thanks and sorry I neglected to update you!

    Mike

  • 0 in reply to Mike Heim
    TI__Guru**** 168605 points

    Great news Mike!

    Thank you for the update and let us know if you need help with anything else.