Re: USB port blew -- why?

From: JAD (Kapasitor_at_coldmail.com)
Date: 10/07/04 

Date: Wed, 6 Oct 2004 23:41:31 -0700

what main board? FIC ECS MSI?...usb blew cause the board blows.

"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
news:755e968a.0410031718.36d14f87@posting.google.com...
> One of the ports of my NEC-based USB 2.0 card quit working because
the
> National Semiconductor LM3526 power controller chip failed. I'm
> pretty sure that I didn't zap it with static (I always touch the
> outher metal shell to the computer case before plugging it in) or
try
> to plug it in backwards. The data *** for the LM3526 says that
it's
> protected against voltage, current, and even temperature, so what
> happened?
>
> National Semiconductor says that each USB port must have a 120uF or
> larger tantalum capacitor between +5V and ground for protection
> against transients that occur during hot-plugging, and NEC's example
> schematic for their uPD720100A USB 2.0 chip shows the LM3526 using
> 150uF aluminum in parallel with 0.1uF ceramic. But my USB card has
> only a 100uF aluminum capacitor and maybe a ceramic capacitor in
> parallel for this. Could this be why the USB port got zapped?
Would
> it help to solder a tantalum in parallel as well? Will it hurt to
add
> it?