At 08:32 AM 11/26/02 -0700, you wrote:
>Given that an MOV is used to shunt high voltage spikes, but not actually
>carry current, do the traces have to be bulked up for them?
>
>In other words, would a 20mil trace suffice for a MOV running at 115VAC or
>would it act like a fuse when I hipot test it?

It has to carry current (could be hundreds of A) for a short period of
time during a surge. Also, when the MOV gets around to failing, it will go
short almost for sure. You should decide whether you would prefer the traces
to vaporize before the device fuse goes or not.

When you use a Hipot tester, the current is limited to some mA so it
won't be a problem.

>Anyone had any experiance with putting them on a board?

Sure. Experience, anyhow. Usually they are so close to the device being
protected or the source of the surges that trace length just isn't an
issue, but I think more like 100mils would be appropriate for a small MOV.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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