USB stops responding
in [Hardware]
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From: Paul on 20 Mar 2006 21:31 In article <1142900031.172797.257130(a)j33g2000cwa.googlegroups.com>, "larry moe 'n curly" <larrymoencurly(a)my-deja.com> wrote: > Paul wrote: > > > > > Kaboom. Another victim of ESD induced latchup. The USB ports > > inside the Southbridge are burned (just the pad driver area). > > This is the only public explanation of the problem. > > > > http://tw2005.giga-byte.com/Motherboard/Support/FAQ/FAQ_456.htm > > It's not just ESD but also current surges. > > I'm always careful about ESD and touch the metal shell of any connector > to the computer case before pluggiing it in, but my USB card was > damaged anyway. The manufacturer said that it was because the tiny > LM3526 chip blew, which, ironically, is designed to protect against > current surges. The spec sheet for the chip mentioned that each USB > port was supposed to have a 120uF or larger tantalum capacitor across > it to supply current during plug-in, but my USB card had only 100uF > regular alumium capacitors. The version of this card sold by Maxtor > had 220uF capacitors instead. That is a dual port chip. I wonder if someone got greedy and tried to run four ports off the one chip ? Otherwise, it seems pretty heavily armored. http://www.national.com/ds.cgi/LM/LM3526.pdf I have my suspicion there is more to the Intel ICH5 issue than has been publically reported. There was one failure reported by a user, where the chip burned right after doing a restart from Windows. That doesn't suggest the user was adding or removing cables at the time, and makes me wonder if there isn't a problem with the +5V used to bias the chip, and its sequencing. It is like there is more than just sensitivity to static, and other things can trigger the problem as well. But the vast majority of descriptions read "I just plugged in my Cruzer, when it died...". More failures from the 2x5 USB headers, than from rear USB ports. On some motherboards, the +5V appears to come from a Polyfuse, followed by an electrolytic to prop up the rails. In that case at least, it is a bit harder to blow out the power path, as the Polyfuse (automatically recovering fuse) is pretty good. I wouldn't think the LM3526 approach would be that common. Paul
From: larry moe 'n curly on 21 Mar 2006 06:10 Paul wrote: > In article <1142900031.172797.257130(a)j33g2000cwa.googlegroups.com>, "larry > moe 'n curly" <larrymoencurly(a)my-deja.com> wrote: > > I'm always careful about ESD and touch the metal shell of any connector > > to the computer case before pluggiing it in, but my USB card was > > damaged anyway. The manufacturer said that it was because the tiny > > LM3526 chip blew, which, ironically, is designed to protect against > > current surges. > That is a dual port chip. I wonder if someone got greedy and > tried to run four ports off the one chip ? Otherwise, it > seems pretty heavily armored. > > http://www.national.com/ds.cgi/LM/LM3526.pdf > On some motherboards, the +5V appears to come from a Polyfuse, > followed by an electrolytic to prop up the rails. In that > case at least, it is a bit harder to blow out the power > path, as the Polyfuse (automatically recovering fuse) is > pretty good. I wouldn't think the LM3526 approach would > be that common. My Maxtor USB card has four ports but only a single LM3526 to protect all of them. At least it has one Polyfuse per USB port, unlike some cards where each Polyfuse protects a pair of ports. I've seen mobos that were designed for Polyfuses but had jumper wires installed instead. Among them were a couple of PC Chips models, including the one that quit working just five hours after I got it, but not mobos from Gigabyte, Abit, or Asus/Asrock. I don't remember about MSI, but I think theirs have Polyfuses.
From: kony on 21 Mar 2006 06:38 On 20 Mar 2006 16:13:51 -0800, "larry moe 'n curly" <larrymoencurly(a)my-deja.com> wrote: > >Paul wrote: > >> >> Kaboom. Another victim of ESD induced latchup. The USB ports >> inside the Southbridge are burned (just the pad driver area). >> This is the only public explanation of the problem. >> >> http://tw2005.giga-byte.com/Motherboard/Support/FAQ/FAQ_456.htm > >It's not just ESD but also current surges. > >I'm always careful about ESD and touch the metal shell of any connector >to the computer case before pluggiing it in, but my USB card was >damaged anyway. The manufacturer said that it was because the tiny >LM3526 chip blew, which, ironically, is designed to protect against >current surges. The spec sheet for the chip mentioned that each USB >port was supposed to have a 120uF or larger tantalum capacitor across >it to supply current during plug-in, but my USB card had only 100uF >regular alumium capacitors. The version of this card sold by Maxtor >had 220uF capacitors instead. I'm beginning to wonder if these (*problematic*) USB devices themselves have too much capacitance. There's a pretty low limit on how much the device (peripheral, not internal USB card or integrated subcircuit) is supposed to have, might be 100uF or even lower but I don't recall the exact figure.
From: kony on 21 Mar 2006 08:42
On 21 Mar 2006 03:10:54 -0800, "larry moe 'n curly" <larrymoencurly(a)my-deja.com> wrote: >I've seen mobos that were designed for Polyfuses but had jumper wires >installed instead. Among them were a couple of PC Chips models, >including the one that quit working just five hours after I got it, but >not mobos from Gigabyte, Abit, or Asus/Asrock. I don't remember about >MSI, but I think theirs have Polyfuses. MSI do, even PCChips-made Shuttle boards do. |