Part Number:ADS1115
Dear all,
I have a device that I want to measure its IV curve, the range of the voltage that this device works on is from -3 to 3 V as a maximum, so I produce a ramp voltage from 0 to 3 V using MSP430FR6989 and connect it to a RC filter as in the attached figure, then I connect LM324 opamp to have the bipolar range of the signal from -3 to 3 v, finally the device is connected to the opamp's output, until here everything is fine but once I connect the AN1 of the ADS1115 (connected to pi) to the device the negative side of the opamp's output drops from -3 to -1 V.
I replaced this opamp with TL084CN and I'm still have the same problem.
I connected another opamp as buffer but it does not work.
Also, I reduced the range of the signal to be in the range of -1 to 1 V , here I do not see a cutoff of the negative side of the waveform but I got a wrong curve.
The GND of the ADS is connected to the analog circuit with the GND of the MSP then I separated the GND of the MSP and the ADS from the analog circuit.
Could you please explain to me if this ADS is capable of reading a negative voltage or not, I read in many documents it reads from 0 to 5 V, does that mean peak to peak range? by mean if the signal is from -2.5 to 2.5 V is that ok?
The other thing I'm looking for is the common input voltage of the opamp, if someone can explain this point for me I will appreciate that.
Thank you,
