EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: tomy983 on February 25, 2016, 10:32:02 pm
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Hi!
I am playing with a little breakout board from Adafruit, which has on board this adc
http://www.ti.com/lit/ds/symlink/ads1115.pdf (http://www.ti.com/lit/ds/symlink/ads1115.pdf)
I have read the datasheet, and it is mostly clear.
On the absolute maximum ratings, it states that Analog input voltage to GND must be –0.3 to VDD + 0.3
On my bench I am powering the breakout board, hence the adc with a 5V supply, but the signal I am analysing comes from the output of a linear position transducer, powered at 24v with a separate supply.
I am wondering, if I cut my 5V supply first, so that the output voltage of my sensor is still present I should be over the maximum ratings but the adc has no VDD...
Would this damage the adc or not?? :-//
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It is not recommended to do this. Even if there will be no permanent damage, your device will be powered though internal clamping diodes.
Do as it says in the DS: If it is possible that the voltages on the input pins may violate these conditions, external Schottky clamp diodes and/or series resistors may be required to limit the input current to safe values
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Thank you, Alex.