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Negative voltage on input MCP6071 operational amplifier ?

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Astrid

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I have MCP6071 powered +3,3V, input on + Input is 0-500mV over 10k Ohm resistor, but in case of a fault, the input may appear negative voltage -0.8V.
In eletrical characteristic in section Absolute Maximum Ratings, is allowed maximum negative voltage -0,3V.
The question is what happens when -0,8V?
Over current flows through the protection diode or destroyed input?
In other words, I have to use external protection diode, for example, BAT54 or not?
 

Hi,

you have a 10k resistor. Is the -0.8V on the OPAMP side or the input side of the resistor?

If on the input side, then I see no problem, because current is limited to below 100uA. Datasheet says it must not be more than 2mA.
As far as I know the max voltage limit and max current limit are alternative. (in opposite to other max. specifications) This is true with all OPAMPs as long as it is not statetd otherwise in the datasheet.

Especially here with your OPAMP there is a chaper 4.1.2 that describes the input protection.


Klaus
 

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