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TLE2142: TLE2142QDRQ1 Input Bias current fault

Junwoo Kim
Prodigy 40 points

Part Number: TLE2142

Hi.

I am using TLE2142QDRQ1 Op amp for inverting amplifier.

We tested it for a long time at low (-40degC), and high (90degC) temperatures.

The op amp bias current became strange.

(Bias current direction was changed. There is a resistor which is connected to op amp positive input. I measured the voltage drop of the resistor.)

During the test, I found that positive input resistor has a partial crack, so the resistance was changed rapidly and intermittently.

My question is, the partial cracked resistor can damage op amp input?

Thanks.

  • 0
    TI__Guru* 93105 points

    Hello Junwoo,

    The resistor connected between the TLE2142QDRQ1 non-inverting input and whatever voltage level there is on the on the other end provides a current path for the op amp's input bias current. If that resistor is cracked and changing value it will cause the output referred voltage offset to move around with the particular resistance the resistor exhibits at that moment. 

    If the resistor completely opens and becomes infinite resistance the input bias current will no longer have a return current path. The input transistor on that side of the input differential pair will shut down. If that happens that output voltage will move to one of the maximum output swing levels. Although the op amp will no longer operate as a linear amplifier I would not expect it to be damaged by that occurrence.

    Regards, Thomas

    Precision Amplifiers Applications Engineering