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LMP2012QML-SP: max. current at input pin

Daniel Bieri
Prodigy 30 points

Part Number: LMP2012QML-SP

As is common for OPAMPS, the datasheet of the LMP2012QML-SP specifies that the input voltage must not exceed the supplies (absolute max rating for differential and common mode input range).

However, i noticed that the absloute max ratings also specify a maximum current of 30mA at input pins. Does this limit reflect max. rating of clamping diodes at the input of this OPAMP? i.e. is the device safe even if the input voltage exceeds the supplies, provided that the current remains limited below 30mA?

kind regards,

Daniel

  • 0
    TI__Guru 72991 points

    That's correct.  The Absolute Maximum Ratings table specifies maximum input current when the input common-mode voltage exceeds its rails (through forward-biased ESD diodes).  For as long as the input current is limited to 30mA or less (for example by adding a series input resistor), no damage will occur.

  • 0 in reply to Marek Lis
    Prodigy 30 points

    thanks for the quick reply. Now the follow up question popped up whether the device performance could be degraded in this condition. Respectively if there is a maximum input current for which we can be sure that the OPAMP performance is not degraded?

    In our application it is possible that an input voltage is applied to the amplifier while the OPAMP is not powered. We do have a resistor in series with the OPAMP input which limits the current flowing into the device. However, this condition (i.e. current being driven through the OPAMP ESD diodes) can last >1s and occur in the order of ~1000 times over the circuits lifetime (each time at power up). 

  • 0 in reply to Daniel Bieri
    TI__Mastermind 27430 points

    Daniel

    As a rule of thumb, when events are expected to happen on a regular basis, say every time the system powers up, we recommend 10x lower than abs max.  ESD diodes are just not intended to be exercised for DC protection but since high speed ESD transient events can be higher current (granted for much shorter times than 1sec), we would not expect any long term damage to occur.  So if increasing input resistance does not impact system performance, increasing to limit current to 10x smaller than abs max is what we would recommend.

    Chuck