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Thread: Is LLC topology reliable?

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    Default Is LLC topology reliable?

    Some claim that LLC is not reliable as forward because it's more complex, is LLC used in super high-reliability needed applications too?

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    LLC is used in the medical, server, and other industrial applications. It's reliable enough.

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    Quote Originally Posted by rgbodosk View Post
    Some claim that LLC is not reliable as forward because it's more complex, is LLC used in super high-reliability needed applications too?
    As Tator Tot said: LLC is used in everything.

    These "some" people you are talking to are talking at a very high level. Similar to saying "the grass is brown because it is not green" instead of explaining that the grass lacks the nutrients required to produce chlorophyll."

    ANY circuit with more components is less reliable than one with many components. It's a numbers game. Double the components means twice as many things that can allow it to potentially fail.

    But to flat out say it's more unreliable is false. You can have a double forward that lasts ten years and you can have an LLC last twenty years. Based on empirical data, does that now mean that double forward is less reliable???? No. It's bullshit.

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    It might even be argue that the switching for LLC is much gentler on the transistors than for older designs.

    Take for example a traditional household switch, it will in general switch randomly on the AC cycle; now add a circuit that has it switching at the zero point, more complicated but the switch itself may last much longer.
    Last edited by ashiekh; 11-16-2019 at 01:11 PM.

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    I'd guess that there are certain components whose expected lifetime in a Power supply is MUCH less than all the other components, like the primary side FETs and fan (which are also found in all PSU, regardless of topology). So it's not wholly true that twice the components = twice as likely to fail.

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    I would have said the secondary capacitors and fan, and left out the switching transistors; but that is just me. I tend to rebuild old supplies with top grade secondary capacitors and oil the fan to leave a unit that may endure longer than the new unit did; or at least that is my hope.

    My video card GPU has 1.8 billion transistors, but I anticipate an almost indefinite lifetime as it seems to run rather cool and has no fan.
    Last edited by ashiekh; 11-16-2019 at 05:41 PM.

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    Quote Originally Posted by ashiekh View Post
    I would have said the secondary capacitors and fan, and left out the switching transistors; but that is just me.
    Huh, I seem to recall JG saying somewhere that cap failures in modern PSUs are pretty rare and that it's mostly the FETs that die. I must be mistaken though... My bad.

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    Rest assured that the Guru knows, and that I am just behind the times.

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    From RMA stats I cannot see any difference between LLC and Double forward. Be aware RMA stats only cover the warranty period for each PSU though. What happens later is not relevant for RMA any more.

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