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LM2596: Reverse current protection of LM2596(5V out)

Tai Pham
Prodigy 21 points
Part Number: LM2596

Hi all, I want to ask some questions about Reverse current protection of LM2596(5V out):

1) With Figure 1: I see that Absolute maximum ratings of Pin4 (Feedback pin) is -0.3to25V. When LM2596 is operating if I apply 28V to Point1 by mistake, Are LM2596 and Cout (Rate voltage=10V) damaged ?

2) With Figure 2: when LM2596 is operating if I apply 28V to Point1 by mistake, Are LM2596 and Cout (Rate voltage=10V) damaged ? If this solution is ok, Have any disadvantages with this solution ?

3) Have any application notes or technical documents about Reverse current protection of LM2596 ?

  • +1
    TI__Guru 57555 points

    Hello

    In figure 1, the 28V is beyond the rating of pin 4 (25V).  Therefore damage will occur.

    In figure 2, the device and output capacitor will be protected.  The voltage to your load will be reduced by the voltage drop of the diode.

    Please also see app note SLYT689 and SLVAE57 for more information.

    Thanks

  • 0 in reply to Frank De Stasi
    Prodigy 21 points

    Dear , Thank you for your answer!

    I would like to ask a few more questions.

    In Figure 3, When LM2596 is operating if I apply 16V to Point1 by mistake,


    Question_4) In figure 3, Is BAT (non-rechargeable) damaged ?


    Question_5) If the BAT(non-rechargeable) is damaged in figure 3, Is the solution in figure 4 ok ?

  • 0 in reply to Tai Pham
    TI__Guru 57555 points

    Hello

    You may have your figure numbers mixed up.  I think that figure 5 is good.

    However, in figure 3 the diode will also block any voltage going to the battery.

    Thanks

  • 0 in reply to Frank De Stasi
    Prodigy 21 points

    Hi ,

    Sorry for the unclear between figure numbers and question numbers. So, I have edited it.

    You said: "in figure 3 the diode will also block any voltage going to the battery" . But I think that in figure 3, 16V(at Point 1) will forward bias the diode so that the current will return to the non-rechargeable BAT and non-rechargeable BAT will damaged.

    Am I correct in thinking so? 

    Regards !

  • 0 in reply to Tai Pham
    TI__Guru 57555 points

    Hello

    Yes; you are correct

    Thanks