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Original question:

LM2941C: Back powered LM2941SX behaviour

LM2941: Reverse current protection

Kenji Ohno1
Genius 5095 points
Part Number: LM2941

Hi Team

Is a reverse current protection circuit built in?

I would like to know the back electromotive force resistance.

What kind of protection is “Mirror Image Insertion Protection”?
Best Regards,
Kenji

  • 0
    TI__Guru 55940 points
    Hi Kenji,

    LM2941 does not include reverse current protection. If you are expecting a reverse current event (Vout > Vin) in your application, you will need to add external reverse current protection. Commonly this is done using a Schottky diode from Vout to Vin.

    The "Mirror Image Insertion Protection" is an older phrase for through hole packages that refers to the fact that the TO-220 package will survive being inserted backwards. In this case OUT will be flipped with ADJ and IN will be flipped with ON/OFF- not OUT flipping with IN.

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Genius 5095 points

    Hi Quote,

    Thank you for your answer.
    For example, if Vout = -200mV when Vin = 0V, will there be a problem?
    There is a 5.6V Schottky diode in the internal circuit.
    What is this role?
    Best Regards,
    Kenji
  • 0 in reply to Kenji Ohno1
    TI__Guru 55940 points

    Hi Kenji,

    LM2941 is intended for positive voltage applications only.  A voltage on OUT that is lower than the voltage on the GND pin(s) may result in damage to the regulator by allowing current to flow through internal paths from GND to OUT.  This risk can be reduced by adding an external Schottky diode between GND and OUT.  This diode will provide a robust path for this current.  A Schottky diode would be used due to its low forward voltage characteristics allowing it to begin conducting when Vout drops slightly below GND.

    Please be sure to always be using our latest datasheet available on TI.com.  The Functional Block Diagram includes a Zener diode to show the internal reference.

    Very Respectfully,

    Ryan