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LMC6482: Inverting Input Open

Tuan Cao
Prodigy 10 points
Part Number: LMC6482

Hello,

I'm doing an FMEA on the LMC6482.  I'm using it as a comparator, and the output is a low.  When the non-inverting input fails open, would the output goes to low to rail?  Also, when the inverting input fails open, would the output goes to high to rail?

  • 0
    TI__Guru* 93105 points

    Hello Tuan,

    Unusual conditions such as an open input pin are not often characterized so we don't have that particular kind of information for the LMC6482.

    The LMC6482 is an ultra-low input current operational amplifier having a typical value of 20 fA. The input pins have more than just a input CMOS FET connected to them. An LMC6482 input also has an ESD protection diode to each supply rail and additional circuitry to reduce the overall input current seen by the outside circuit. Therefore, depending on the each ESD diode's leakage current and the other currents involved in the input circuit, the current direction may not be predictable in terms of whether it flows in, or out, of the device input pin. And that determines if the output will be high, or low, when an input pin is opened. Therefore, even though the output may behave a certain way for some devices, it may be the opposite for others.

    Regards, Thomas

    Precision Amplifiers Applications Engineering