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Suggestion Required on Reverse current protection circuit

kumar singh
Guru 10875 points

Hi,

I am designing an application which is powered through either of 2 sources rated 12V@6A.  One is POE and other is through power Jack. I want to implement reverse current protection circuit implemented on my design so that POE output can be isolated in case DC Jack is used as power source. By default POE is used as power source but we may require to power the system through external DC source. Hence I want to have design like if DC Jack is used for power, it should not affect POE circuit. Also when POE is used as power source and in meantime DC source is plugged in, both should not get affected with each other.

Normally, we can think of using schottky diode on output of both POE and DC source but since the power requirement is more(60-70W), we don't want to waste power(which comes to be 4-5W) specially POE power.

Can anyone please suggest solution for this design?

Regards

Narendra Singh

  • 0
    TI__Genius 16305 points
    Hi Kumar,

    Can you please take a look at LM74700 device, this is an ideal diode controller which drives external NFET for ORing two power supplies.
    Two LM74700 + NFET can support ORing of POE power and DC Jack.

    Do you also require hotswap or inrush current control for this applicaiton?

    Regards,
    Kari.
  • 0 in reply to Karikalan Selvaraj
    Guru 10875 points

    Hi Karikalan,

    thanks for your suggestion. i am using mosfet with mosfet driver for isolating the 2 power but when i plugin the power through external source, POE section loads the external source(maybe current flows through mosfet parasitic diode). Below is my design which is not working as expected.  Hence i am thinking if the part you have suggested is going to resolve my problem. do need hotswap and inrush current control for my application.

    I want to protect POE(12V_POE) from reverse current protection in case power is applied through Power Jack source. Temporarily i am using diode at power Jack input(D13 in picture) which need to be replaced with some protection circuit