ADS1115 and negative voltages

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tben
 
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ADS1115 and negative voltages

Post by tben »

Will the ADS1115 on differential mode directly measure negative voltages, within the range of the gain setting of course. I seem to read conflicting info on this.

For instance, on this page:
https://learn.adafruit.com/adafruit-4-c ... onnections
Under 'which should I use' it would seem you can measure negative voltages. But under 'differential connections' the warning box tells me you can't directly read negative voltages. When I look at the data sheet for the ADS1115, the full scale input voltage would seems to indicate negative voltages can be directly read.

Can someone let me know for sure if negative voltages can be measured directly? I don't want to destroy the ADS1115.

Thanks

[Tim]

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adafruit_support_bill
 
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Re: ADS1115 and negative voltages

Post by adafruit_support_bill »

Differential measurements measure the difference between two signals. But all input voltages must be between GND and VCC. A 'negative' reading occurs when the voltage on A0 is less than the voltage on A1.

For example: If the voltage on A0 is 1.0V and the voltage on A1 is 3.5v, the measurement will indicate a differential of -2.5v.

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