Motherboard Voltage Regulators

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 I've just cooked the (3.3V???) voltage regulator on my motherboard.
I'm trying to find a replacement for it, it's an Infinity LX83838. I
was wondering if anyone here has a clue as to what exactly it is, and
it's pin-outs. Since my processor, RAM, and cards all survived it going
up in smoke, and I have spares, I have nothing to loose by replacing it
and trying my dead board(Gigabyte GA-5AA).



Re: Motherboard Voltage Regulators

You may want to ask in

I couldn't find Infinity, but by entering the part number at (sort of like Ebay for chips), I saw Linfinity listed
several times, and their website is
It's possible that the part number isn't LX83838 but LX8383b: is a source of many chips and can be fairly cheap.

Re: Motherboard Voltage Regulators

On 29 Aug 2005 01:49:16 -0700,

Quoted text here. Click to load it

I agree with LM&C, it is probably a Linfinity LX8383b.  You
might need to determine if it's a fixed output type (has a
3.3 on it) or adjustable (usually "Adj" on it).  If you can
trace the circuit you can also see if the ADJ pin goes
straight to ground or has voltage divider resistors.

It has a fairly standard pinout for a linear LDO regulator,
left to right the pins are,

 Input | Output | Adjust

However, you need not use exact same thing again, and/or you
might consider how/why it failed.  Generally they have
shutdown protection so it might be something more

There isn't much copper there on your board to 'sink that,
and since you're asking about replacement should we presume
it's not soldered down?  If so, AND presuming the output is
through the 2nd lead rather than the 'sink, you might be as
well off getting a TO220 case style and mounting it standing
upright with a small heatsink, that heatsink having an
outline no larger than the area below the original regulator
(so it's electrically isolated), screwing down that 'sink
through the original hole.  Alternately, if it was just
screwed down with no thermal grease (and the output is
through the pin instead of the 'sink tab) you might put a
dab of grease under the replacement before screwing it down.

What I've just written may not be obvious to implement,
harder to describe briefly than to visualize it.  

The board itself isn't worth much, are you confident the
cause of the regulator failure has been isolated?  Perhaps
shorting capacitors or some other fault has damaged it?
Basically I"m inquiring about those details you may know but
have not disclosed, such as how you know it's cooked.
Generally buying one of these less common (high, 7A LDOs)
may cost $10 plus shipping, maybe plus a small-order

Re: Motherboard Voltage Regulators


Quoted text here. Click to load it

Err, see the datasheet LM&C linked, as what I wrote above is
only "left to right" if looking at one with the tab pointing
down, lettering upside down too.

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