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SN74LVC1G10: Input pin being held @ 2~2.2V after removing 5V input signal

Robert Schumann
Prodigy 30 points
Part Number: SN74LVC1G10

I am using this device and encountered a very strange situation. 

Static part of operation:  Pin A,B have 5 Volt positive input, VCC is 5V.

Pin C has a 133K ohm resistor (Rc) to ground, no capacitors.  I apply 5V to Pin C get expected change to output Y.

When I remove 5V from Pin C the Pin almost always settles at ~2.3V.   If I ground Pin C directly (bypassing the 133K ohm ground resistor) Pin C goes to 0 and stays there until 5V re-applied.

Why is this occurring, and how do I fix it?

Note because of very limited feed current for my Pin C signal I cannot do the obvious fix of just lowering Rc's value.

  • 0
    Guru 317360 points

    The specified input leakage current is at most 5 µA (and should be much less at normal temperatures). That voltage implies a current of 17.3 µA through the resistor.

    Might that current leak through dirt or a solder bridge? Is it possible that this chip is damaged (by ESD or something else), and that a replacement fixes it?