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Original question:

PGA300: PGA300 DAC Calibration

PGA300: PGA300

Ed Payne
Intellectual 375 points
Part Number: PGA300

0-10V output application, during DAC calibration,

766=0V with reading 1.47V, it should be around 0V

1800=5V with reading 4.76V, it should be around 5V

2700=10V with reading 5.45V, it should be around 10V

DAC Gain = 10V

Thanks!

P.S. I do not have problem to 0.5-4.5V application.

  • 0
    TI__Mastermind 31655 points

    Hello Ed,

    The output at each of the default DAC codes on the calibration page will not necessarily match your desired output. These codes can be changed to be closer to the desired value, but once the calibration is complete it should calculate the correct DAC codes to generate the desired voltage. Have you completed the calibration procedure and tried the updated DAC codes?

    Also, just to be clear: my understanding is that you have manually set the DAC to each of the codes from your post and measured the voltage output in each case (1.47V when set to code 766, etc.). Is that correct?

    Thanks,

    Scott

  • 0 in reply to Scott Cummins
    Intellectual 375 points

    Hi Scott,

    At 766 I set 0V, then "Write DAC code", but reading of precision meter was 1.47V, 1800 was 4.76V, 2700 was 5.45V, so there was no way to go thru "DAC calculation" with 1.47/4.76/5.45 DAC codes.

    Thanks,

    Ed

  • +1 in reply to Ed Payne
    TI__Mastermind 31655 points

    If the DAC gain is set to 10V/V you should be able to get up to 10V without maxing out the DAC codes. It looks like you may be drawing too much current from the DAC gain stage and it's causing the voltage to droop. What kind of load do you have on the output? The short circuit source current is about 27mA, so you shouldn't have a load resistance lower than about 400ohms.

  • +1 in reply to Scott Cummins
    Intellectual 375 points

    Hi Scott, only output is precision voltage meter, the short circuit source current is about 30mA. 

    Because OWI limits 5V, to 0-10V output, in DAC calibration, "Raise VDD" will be needed.