• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 49 subscribers
  • Views 668 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV2374 input overvoltage protection

Gene Mirro
Prodigy 160 points
Other Parts Discussed in Thread: TLV2374

My positive power supply is +5V.  What happens if I apply +9V to the noninverting input through a 127K resistor?  Will the op amp be damaged?  Does the TLV2374 have input ESD protection?  Thanks.

  • 0
    TI__Guru* 93105 points

    Hi Gene,

    The TLV2374 does have input, output and power supply ESD protections. These cells are all off under normal, in-circuit operating conditions. 

    The input ESD cell consist of steering diodes that connect from each input, to each of the internal supply rail. If the input is driven by a voltage source beyond the supply rail, the diode can be forward biased and conduct current. Most often that current ends up being conducted by the amplifier because the power supply can't sink the current. The input over voltage takes over supplying supply current to the amplifier that power supply normally provides.

    If the input current is limited by an external series resistor only so much current can flow in the diode circuit when it becomes forward biased. Using the +9 V input, +5 V supply, a diode drop of 0.6 V and the 127 K resistor, the current is:

    I = (9 V - 5 V - 0.6 V) / 127 k = 26.8 uA

    About 3.4 V of th einput voltage is going to drop across the 127 k resistor, which places the input at 5.6 V. It is very unlikley that the TLV2374 input will be damaged. with a current that low, or a voltage of that level.

    A series input resistance is often an effective means for limiting the input current should during an electrical overstress (EOS) event.

    Regards, Thomas

    PA - Linear Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 160 points

    Thanks, Thomas.  I think you're correct.  We have been running the TLV2374 in this condition for a long time, and it seems fine.  I just wanted to understand it better.