ADC128S102-SEP: The ADC is saturating at 4.5V

Naman Vaidya

Part Number: ADC128S102-SEP

Hello,

I am using ADC128S102-SEP in one of our design and we realized that the ADC reading is saturating around 4.5V. Wanted to check if this is true or there is some failure in our case also we are using a unity gain opamp LMP2012WG-QMLV before the Analog input. The Va is supplied with 5V and the Vd is at 3.3V and the OPAMP is powered by same 5V rail.

For the input of the OPAMP we have a potential divider and lower divider is a "pot" for doing this sweep. It would be great if you can give me some input on the issue.

9 months ago

0 Samiha Sharif 9 months ago

TI__Expert 6671 points

Hi Naman,

Thanks for your question. When you probe the output of the amplifier/input of the ADC, what is the voltage range? When probing the VA supply rail, is it actually at 5V? Could you please share a schematic?

Best,

Samiha

0 Naman Vaidya 9 months ago in reply to Samiha Sharif

Prodigy 20 points

Hey,

Sharing schematic will be tough on the open forum, but a very reduced version of the schematic is in the image attached.. The issue unity gain amplifier ranges till 5V and the range changes from 0.1 to 5V but the ADC saturates and sends 4096 to the micro after 4.5V.

0 Samiha Sharif 9 months ago in reply to Naman Vaidya

TI__Expert 6671 points

Hi Naman,

I will contact you via email.

Best,

Samiha

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ADC128S102-SEP: The ADC is saturating at 4.5V