ADC128S022: Conversion result has variation

Michiaki Tanii

Expert 5070 points

Part Number: ADC128S022

Hello team,

Our customer observed the below phenomenon and could we share their schematic internally ?

Conversion results has variation by SCLK as following.

They input 6.00V to A/D converter and the ideal conversion result will be 67C.

SCLK Sampling frequency Conversion results

3MHz 93.75kHz 68C

1.5MHz 46.875kHz 6A3

Please give your advice and let me share their schematic internally to review it.

Thank you and best regards,

Michiaki

over 6 years ago

0 Michiaki Tanii over 6 years ago

TI__Expert 5070 points

Hello team,

Please give your advise.

Thank you and best regards,

Michiaki

0 Michiaki Tanii over 5 years ago in reply to Michiaki Tanii

TI__Expert 5070 points

Hello team,

Sorry for pushing you but please update the status.

Thank you and best regards,

Michiaki

0 Tom Hendrick over 5 years ago in reply to Michiaki Tanii

TI__Guru**** 183361 points

Hi Michiaki,

For a 6V input to give an ideal conversion from the ADC128S022 of 0x67C, I'm going to make a couple assumptions. First is that you are powered from 5V and second is that you have some sort of voltage divider dropping the 6V to ~2.03V at the input pin of the ADC. A schematic would be nice, but in the meantime, please review the TI Precision Labs - ADC's video series on driving SAR converters (topics 7.1 through 7.5) and see if you can get some improvements on the conversion results.

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ADC128S022: Conversion result has variation