PGA300: PGA300

Ed Payne

Part Number: PGA300

Hello,

My case is 0-10V and 0-5 psi differential.

1) If I set up DAC HEX 0/1350/2700 related to 0/2.5/5 psi, calibration does not work, WHY?

2) If I set up DAC HEX 5/1350/2700 related to 0.01/2.5/5 psi, DAC calibration works, and calibrated at 0.01/2.5/5psi, ADC works too.

BUT at 0 psi it is consistent 0.0075 psi off (0.15% accuracy), and at 2.5 and 5 psi accuracy is 0.02% to 0.03%. WHY?

Please advise, thanks in advance.

over 2 years ago

0 Scott Cummins over 2 years ago

TI__Mastermind 31655 points

Hi Ed,

You will have to check the voltage output with a DAC code of 0. I don't believe it will go all the way to GND, so there will be some small voltage as a minimum. If you set your desired voltage to be anything lower than this, there will always be some amount error that is greater than the error at another point that it can fully reach.

Regards,

Scott

0 Ed Payne over 2 years ago

Intellectual 375 points

Hi Scott,

I set up DAC_Code = 5, Desired_V = 0.01V, do you mean I have to set HEX = 0, and then Desired_V as lower as possible?

Thanks.

0 Scott Cummins over 2 years ago in reply to Ed Payne

TI__Mastermind 31655 points

Hi Ed,

I mean to test manually on the DAC settings page, and setting the DAC to several of the lowest codes to see what the actual minimum output is. I would check from code 0 to code 10 or so to see how the output changes, and what the lowest output can be.

Regards,

Scott

0 Ed Payne over 2 years ago in reply to Scott Cummins

Intellectual 375 points

Hi Scott,

When I try DAC HEX from 0 to 10, how should I set Desired voltage? in proportion to HEX (0-2700)?

Thanks.

+1 Scott Cummins over 2 years ago in reply to Ed Payne

TI__Mastermind 31655 points

Hi Ed,

Use the DAC settings page. You don't have to go through the calibration right now. The point of this is just to set a specific DAC code, and read the output voltage for that code.

If the DAC code at 0 outputs a voltage higher than 0V, you will not be able to reach a 0V output regardless of the calibration. This will help determine what the minimum output voltage is.

Regards,

Scott

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PGA300: PGA300