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I am trying to use MSP432 on chip 14 bit ADC to sense output from a current sensing op-amp.

I am getting a large reading error from my ADC compare to the multimeter reading.

Do I need to have a front end amplifier to buffer the input to ADC, or can I directly sense it?

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  • \$\begingroup\$ Which DMM reading Iin, Vout or both? YOu need to verify MAX gain then verify ADC operating with offset and gain calibration if necessary. Could be like a ADC coding error or pulse averaging error \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Oct 3 '16 at 4:25
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    \$\begingroup\$ To figure out what the actual problem is, it would help to know what is the actual current and what does your circuit read, what shunt resistor you used, what was the load, and what is multimeter's burden resistance. \$\endgroup\$ – The Photon Oct 3 '16 at 4:52
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Do I need to have a front end amplifier to buffer the input to ADC, or can I directly sense it?

Considering this circuit on the first page of the datasheet, I suspect the answer is going to be, "No, you do not need buffering."

Typical application circuit

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    \$\begingroup\$ I hope you are OK with the edit (just makes it clearer that you are directly answering the OP's question). \$\endgroup\$ – Andy aka Oct 3 '16 at 8:25

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