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    Protection of 15A DC power line

    Hi everyone,

    I need overvoltage and reverse polarity protection on a 12V DC line, carrying a current up to 15A. I thought about using a hot swap controller like the LTC4211 as eFuse, which would work for overvoltage protection. Unfortunately however, the chip itself doesn't handle reverse polarity of the input power very well, so although the external FET would protect the rest of the circuit, the LTC4211 itself would also be destroyed in the event of a reverse polarity condition.

    I've considered adding a series resistor in its VCC power line and clamp that with diode to ground to protect the LTC4211 during reverse polarity, but that feels very much like a hack.

    Are there better solutions to solve the problem and implement proper UVLO and reverse polarity protection on a 12V, 15A DC power line?

    Thanks in advance!

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    Re: Protection of 15A DC power line

    hi!

    LM74610 - Reverse Polarity Protection Smart Diode Controller
    try to look at this kind of devices


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    Re: Protection of 15A DC power line

    Hi,

    its not clear to me whether you want to protect the load or the power supply.

    The hot swap controllers are for the load side.

    Klaus
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    Re: Protection of 15A DC power line

    Hi,

    Not sure if you've looked at MOSFETs in power path, page 2 has NMOS and PMOS versions:

    Reverse Current/Battery Protection Circuits



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    Re: Protection of 15A DC power line

    Quote Originally Posted by d123 View Post
    Not sure if you've looked at MOSFETs in power path, page 2 has NMOS and PMOS versions:

    Reverse Current/Battery Protection Circuits
    Thanks for the link, d123!
    May I ask a naive question: is there still a reason to use chips like the LM74610 anno 2018, now that we have P-FETs with such a low Rds(on), as used in the TI application note you linked?



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    Re: Protection of 15A DC power line

    If your circuit design, for whatever the reason, cannot use a ground side Mosfet, then it means that the high side Mosfet must be a P-chan device as outlined in the TI app note.

    P-chan devices, for a given die size, have a higher RDSon. Additionally, N-chan devices are available in a far larger selection of parameters, packages, and manufacturers. For that reason many designers prefer N-chan as high side devices, but those require a charge pump to drive it. The LM74610 provides the charge pump circuit.

    But unless you are designing a high performance circuit, the simple P-chan high side Mosfet is sufficient for most applications..
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    Re: Protection of 15A DC power line

    Thanks for sharing your thoughts! The cost of the LM74610 is quite affordable in volume, particularly considering the losses a P-MOS would incur at currents of 15A, so I'll go for that solution.



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    Re: Protection of 15A DC power line

    Quote Originally Posted by ArticCynda View Post
    May I ask a naive question: is there still a reason to use chips like the LM74610 anno 2018, now that we have P-FETs with such a low Rds(on), as used in the TI application note you linked?
    Naïve answer so as not to seem ignorant when asked something: Regarding the application note, I had only paid attention to the idea of placing N/PMOS in supply line, hadn't read about the IC, I often read app notes and datasheets to get the general idea, but I have learnt something from your and especially Schmitt Trigger's replies, and I only saw your reply after Schmitt had answered it so well.



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