soligen2010
commented
8 years ago In the data sheet absolute maximums it says vdd_+ .3, but the electrical characteristics section that says the input voltage range is ±4.096/PGA so with a 2/3 pga input voltage can get to 6.144. To be truely safe, best to adhere to both limitations
You may choose to run voltage higher than ±4.096/PGA and have no issues, but technically it is outside the parameters of the datasheet and therefore the behaviors are not defined. I think it is better to leave the comments in the examples conservative because a lot of people don't read the data sheets. Regardless of who was answering on the forum, I think it is best for the comments to be based only off of the official data sheet. People like you who are willing to dig a little deeper can decide for themselves what to do.
On Thu, Aug 4, 2016 at 2:12 AM, Nipun Gunawardena notifications@github.com wrote:
This is not a bug, but what I think is a mistake in the comments. However, since people may design differently because of the comments, I thought I should bring it to attention. In the example code, there is comment that discusses the danger of incorrectly setting the gain on the ADC (here https://github.com/adafruit/Adafruit_ADS1X15/blob/master/examples/singleended/singleended.pde#L15 is an example from singleended.pde, but the comment is in all of the examples).
It says to be careful of setting the gain because a signal that exceeds the upper or lower limits of the gain can destroy the device. However, I don't think that's correct. According to this link https://e2e.ti.com/support/data_converters/precision_data_converters/f/73/t/378122 and this link https://e2e.ti.com/support/data_converters/precision_data_converters/f/73/p/398187/1407689#1407689 from the TI forums, a signal that is greater than the PGA won't damage the ADC, only a signal that is over VDD+0.3V or under GND-0.3V can do that. A signal that exceeds the upper or lower limits of the gain will simply give a 0 or full scale reading.
Anyways, just thought I'd point it out. Thanks!
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madvoid
This is not a bug, but what I think is a mistake in the comments. However, since people may design differently because of the comments, I thought I should bring it to attention. In the example code, there is comment that discusses the danger of incorrectly setting the gain on the ADC (here is an example from
singleended.pde, but the comment is in all of the examples).It says to be careful of setting the gain because a signal that exceeds the upper or lower limits of the gain can destroy the device. However, I don't think that's correct. According to this link and this link from the TI forums, a signal that is greater than the PGA won't damage the ADC, only a signal that is over VDD+0.3V or under GND-0.3V can do that. A signal that exceeds the upper or lower limits of the gain will simply give a 0 or full scale reading.
Anyways, just thought I'd point it out. Thanks!