CCS/UCD3138A: question abut ADC12

liwei qi

Part Number: UCD3138A

Tool/software: Code Composer Studio

I use the board of UCD3138OL40EVM for debug. for ADC debug, I use the code example which is in datasheet(1.11.2). I use the dc-source for give a voltage to the pin of AD00,AD01,AD02. Then use pmbus protocol for report the voltage. I add a debug command to report which i need . But i find that it have 0.3V offset. however, the pin of AD00 voltage is 0V. The pmbus report value is 0.3V. Why?

over 5 years ago

0 Yitzhak Bolurian over 5 years ago

TI__Mastermind 18370 points

Hi Liwei,

As the first step, make sure that the current source connected to AD00 and the current source connected to AD01 are off.

This can be done by making sure that the bits IBIAS_A_EN and IBIAS_B_EN in the register PMBCTRL3 are set to zero.

If the offset stills detected, we will look at other possibilities.

Please also make sure that the voltage source is connected without any resistors in series.

Regards,

0 Ian Bower over 5 years ago in reply to Yitzhak Bolurian

TI__Genius 17090 points

I would also suggest looking at your firmware. An easy way to check and see if your firmware is working correctly is to try changing the voltage, and see if the ADC value changes. If it doesn't, probably continuous polling is not occurring, or the debug firmware isn't working correctly.

0 liwei qi over 5 years ago in reply to Yitzhak Bolurian

Expert 1160 points

Hi, Yitzhak Bolurian:

Thank you very much! I find the reason.

0 liwei qi over 5 years ago in reply to Ian Bower

Expert 1160 points

Hi, Ian Bower:

Thank you for your advise.

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CCS/UCD3138A: question abut ADC12