How can we prevent 19v entering SOC?

[caspian]

Dear Forum Members,

When the high side Mosfet gets shorted, the 19v power easily enters the CPU or PCH without any protection.
I think the buck-converter circuits in laptops should be modified somehow to protect the SOC against 19v when the high side Mosfet gets shorted.
How can we do that?
Can we put a safe isolation between the buck converter circuit and the SOC so that no failure in the buck converter circuit damages the SOC?

Thanks

note: The solution will be useful for both repairmen and manufacturers.

[petehall347]

Re: How can we prevent 19v entering SOC?

clamp or crowbar spring to mind

[mcplslg123]

Re: How can we prevent 19v entering SOC?

Manufacturers knows the solution and have all the know how to implement it but the fact of the matter is they dont want to do it. The aim is simple-so that it doesnt last long enough. A HP loyalist who have faced this type of failure will swear not to buy a HP again and may go for rival brand. But the same happens with other brands-So no brands are actually affected in terms of sale.

Dont think much about the issue-accept it as new reality.

[reformatt]

Re: How can we prevent 19v entering SOC?

The OEM's could put an avalanche diode or some other voltage transient device in there if they wanted to. But they don't. And they could have insisted Intel et al to keep using socketed designs rather than BGA so we could just swap out or even upgrade.

It's built in obsolescence. Repairs are just a necessary evil, people expect it. But the preference would be just swap out devices or replace. Then they don't need to keep parts on hand, warehousing etc. This is the price we pay for new models every year.

[Udemzy]

Re: How can we prevent 19v entering SOC?

The truth whether HP,dell or Lenovo etc,this mobo are not manufactured by them.

[piernov]

Re: How can we prevent 19v entering SOC?

It's not easy. TVS diodes are not perfect: they do not act instantaneously, the I/V slope isn't perfectly straight, they do not have tight tolerances and they'd need to dissipate an insane amount of power before burning.
There may be a better solution to this problem, I'm not an electrical engineer, but I don't know what it is.

[mon2]

Re: How can we prevent 19v entering SOC?

HP and Dell are built by Foxconn. We have been working with Foxconn as a supplier for 20+ years but these are their designs and their BOM. They integrate our products into theirs.

Would an add-on pcb be a solution?

What are the dimension restrictions?

Initial quick thought is to detect the transient and shutdown the charger IC to halt the first 2 mofets.

Not clear but can ask TI as to how many cycles will transpire before the mosfets shutdown.

Just random thoughts...

[caspian]

Re: How can we prevent 19v entering SOC?

I did some research and studied that isolation is often implemented in AC circuits.
In DC circuits, I have not found any practical isolation technique yet that can be used in the restricted space of a laptop mainboard.
Having Socket-based SOC is the most efficient solution that does not need any extra protection circuit.