LDO failure modes?

I can't see that being a possibility. Their temperature after 24 hours is not going to be measurably different from their temperature after 8. At least, not due to their being on. Environmental effects will dominate long before that.

If anything, not being switched on and off should prolong their lives by reducing thermal cycling.

Sylvia.

Sorry, I left out a sentence (actually, two... see below): They were moved to a location that, effectively, has them sandwiched between the back of a cabinet and the wall (connections oriented parallel to the wall -- vertical) so there is little airflow, there.

Second missing sentence: There is also a small, serial configuration memory in the device (which I assume also sits on the 3.3V supply as it configures the USB controller).

(And a bunch of LEDs which seem to be powered from the 5V supply)

If it had hairs and didn't creep back out I'd be careful reaching in :-)

Well, how much heat sink area did they provide? If that is inadequate I wouldn't just replace the LDO with the same device because then it's likely to fail again. Then you need it in a bigger package and with some serious heat sink.

Quite likely but I don't know this hub. We had the typical scenario happen in the living room. Bought a UHF modulator from Radio Shack. A few months later ... *PHUT* ... no more signal. Warranty exchange, new one lasted a few years ... *PHUT* ... gone. Opened it up and they had dissipated something around 1.5W into a skinny "plane" that looked like it wasn't even 1/2oz copper. So I mounted a TO220 instead and provided some serious copper (the real stuff) above the board as a heat sink. It never failed again.

[...]

--
Regards, Joerg 

http://www.analogconsultants.com/

USB hubs should be a simple product, but if you read the reviews on Newegg, they have a high failure rate. Some vendors call their hubs military grade, which I assume in the business means they put in parts capable of the current. For a self-powered hub, that would be half an amp. So in theory, your device is on the edge of failure.

Thermal shutdown shows up as an oscillation. The unit heats up, shuts down, cools off, turns on, heats up again, rinse, repeat. The circuitry has a bit of hysteresis in it, which in turn effects the frequency. You can load down a LDO and watch the oscillation in the lab. That is typically done in bench characterization. I took a look at the ISP datasheet. It takes a fair amount of external circuitry to make this thing into a rugged hub. I can see how some hub designs are crap since they depend a lot on the surrounding glue.

the nearly 500mA Icc is a bit odd, the 500mA is what is available on 5V and you need have at least 100mA per device so afaict you can't have more than two ports and make it selfpowered

yeh it really needs a switch per port

I can understand that a cheap no-name hub would skip on that but I was recently playing with USB on an Acer laptop, shorting the 5V on a USB port causes instant power off

-Lasse

I don't see how you can determine that from the half amp figure. The hub is self-powered so all of *it's* power comes from external power supply (i.e., it places no "load" on the machine to which it's A connector mates).

The issue is that the power that it uses for its *internal* components is at the limit of what the LDO *in* it can provide. (The LDO provides

3.3V -- not 5V -- so it isn't supplying any power to any of the other USB devices which may be attached to the hub). [There is a separate issue in that the power supply that accompanies the product is only rated at 3A. Assuming *only* half an amp was used internally (i.e., the limits on the LDO), then there is only 2.5A available to power the *7* devices that could conceivably be plugged into the hub. In my case, this is not an issue -- I can upgrade the external power supply but don't need to as none of the devices that attach to the hub expect the hub to source their power.]

AFAICT, most of that is present (added), here. IMO, the issue seems to solely lie with the choice of LDO. OTOH, as there are no worst case limits specified for the USB controller (the biggest part of the load that the LDO powers), one can have *some* sympathy for the hub designer(s) -- but not *much*! :>

[see picture upthread]

Huh? We must be talking about two different things (?)

The hub receives power from an external power supply (it may also be capable of being bus powered but that isn't the case, here). Of the 5VDC coming into the device, some is consumed to power the USB controller *inside* the device (and a wee bit for the configuration memory).

The USB controller derives its main source of power from a 3.3V LDO powered off that 5V supply. The LDO is capable of supplying 500mA at 3.3V and the USB controller (chip) *typically* consumes 492mA (when all 7 ports are operating in HiSpeed mode).

[I haven't checked the power requirements for the configuration ROM.]

The devices (eventually) attached to the hub receive their power from the 5V supply (behind FETs). So, the LDO's limitations play no role in how many devices can be *powered*.

[In my case, none of the external devices are powered by the hub]

This device will sense the over current condition -- per port -- and shut down the drive to that port. (As I don't power devices from the hub, I've never checked to see this happen -- nor sorted out how it "recovers"... when the load disappears?? I suspect the LED associated with the port also goes dark...)

One of my tablets often complains of an "over current" event on its USB ports when I attach an external disk drive (powered *by* that port). Curiously, another IDENTICAL tablet never complains when the same disk is attached! (it's just the spin-up current that seems to be an issue)

Den mandag den 13. januar 2014 22.48.15 UTC+1 skrev Don Y:

I think so, my point was that if the controller it self uses that much current it cannot be used self powered because there will be nothing left for the devices

-Lasse

"self powered" == hub has its own source of power (i.e., external power supply)

"bus powered" == hub steals power from the host to which it is connected.

Den mandag den 13. januar 2014 23.06.26 UTC+1 skrev Don Y:

ahh sorry, I got it backwards I meant bus powered

-Lasse

Yeah, I don't think people spend much time considering "mnemonic aids" when they pick these terms! "HiSpeed" vs. "FullSpeed"? WTF? Most of us don't spend our ENTIRE CAREERS writing standards yet they seem to think we'll all have the same degree of familiarity with what they've (arbitrarily) written as they do!

[...]

In politics that works perfectly well. You take in $100 in taxes and from that you spend $167 :-)

--
Regards, Joerg 

http://www.analogconsultants.com/

I've got a box of assorted heatsinks, somewhere. I figured I would just paw through it and see what I could find that fits.

Of course, I will first replace the LDO and verify the hub still

*works*!

The Fuji has *no* viewfinder. So, you "watch TV" while trying to frame the shot. Fine but my eyes have aged to the point that I need to hold the camera farther away than I would like (in order to be able to focus with unaided eyes -- I seldom wear my glasses). But, as you move the "TV" farther away (arms length), spotting the fine detail in the image it is displaying becomes a problem.

With the (electronic) viewfinder -- and "optical compensation" -- I can press my eye up close to the image and adjust the lens in the viewfinder to compensate for the bias in my eye.

SWMBO was tickled when I showed her that she could do similarly with her camera (one thing they don't stress enough is that cataract surgery costs you your near vision, typically)

I've got a couple of SLRs and a collection of lenses. But, I've just never invested in buying a compatible DSLR!

For ages, I would document things with an SLR and "make prints". Then, one day, a neighbor gave me his old digital camera and the idea of NOT having to make prints just blew my mind!

And, not having to *scan* prints to include them in publications!

Now, its a chore to remember to "clean off" the memory card in the camera(s) before it fills (the UI on most cameras sucks when it comes to servicing the media!).

SWMBO now effectively *curses* her digital camera cuz she never

*wants* to delete any of the photos she has taken. As a result, spends a day or more each month sorting and archiving them!

Glad I could do her that favor! (tee hee hee)

That plus a hack saw will do.

[...]

That's one reason I carry glasses even on my bicycle. Also very handy for maintenance stops after something got busted and the tools must come out.

[...]

You don't necessarily have to. I bought an Olympus PEN body (new, no lens) for $160 or so, plus a Fotodiox adapter for $20 from the new Micro-4/3 mount to Minolta-Rokkor mount. And ... bingo ... now I can use all the lenses I have from the old Minolta 35mm set. I just can't use any of that auto-focus and auto-zoom and whatnot because these lenses are 20-30 years old and don't have any of that. Also, I have to remember that a 50mm lens is now effectively a 100mm lens because the sensor is smaller than 35mm film. Meaning my 28mm (which is now like 56mm) became the portrait lens.

When I got this camera the results were stunning. After inserting the

250mm (now comparable to 500mm) I held it out the window and snapped a photo. With the eye one could see some whitish blur in the distance. Hauled the pic onto the PC and that blur became a crystal clear realtor sign. I could read logo, name and phone number. Amazing.

And when you need 100 prints you can upload it to the pharmacy web site and pick them up an hour later.

I wipe it clean immediately after the photos are on the PC and backup server.

My wife is the opposite. She tosses everything that's not really needed anymore.

--
Regards, Joerg 

http://www.analogconsultants.com/

I figured Dremel would probably be more appropriate "shaping" to fit.

I'd be able to fix a bike or a car w/o glasses. I actually have a very mild Rx -- but problem with astigmatism so "edges" aren't as crisp as they should be.

Don't ride a bike (unless I'm traveling beyond my ~3mi each way walking limit and feel lazy :> ). Too many wacko's with automobile licenses! (esp this time of year with all the senile^H^H^Hsenior citizens who decide its too cold to winter where *they* live!)

I wear glass lenses so the "bounce" in my natural walk ends up causing them to slide down my nose -- esp when it is warm out (i.e., practically all the time, here!).

So, aside from driving, it is just easier to live with them off and be willing to tolerate a certain fuzziness in distant objects (I've long since learned to memorize motor vehicles so I know who it is that just honked at me :> )

Never really was "into" photography. Just accumulated stuff as various needs arose. And, always slow to discard things once accumulated! For all I know, there may well be film in the camera bodies that I've never reviewed. If I haven't "missed it" after all this time, it can't have been important! :>

I think I have a 200mm zoom in one of the camera bags. Always felt like a bit of a voyeur even letting people *see* the lens mounted on a camera body! ("Hmmm... I wonder what *he's* looking for?")

I have a small Sony (?) photoprinter that does an excellent job on the "one off" prints I've needed over the years. Typically, something SWMBO wants to (snail) mail to a friend. Or, when making a special greeting card, etc.

I think the only prints we've made in recent years have been enlargements of scenes for SWMBO to use as "subject matter" for her paintings. Insanely inexpensive *not* to take advantage of the larger size!

Ah, I rarely pull the photos onto a PC in the first place! Slide the memory card into a reader and examine them there. E.g., the photo I posted previously went from memory card directly to web site -- no copy persists on this machine.

Someday, the card will be full. Then I'll go through and review all the photos ("Gee, I wonder what *this* was supposed to be?") and erase them.

SWMBO uses them as "studies" for painting compositions, etc. As a result, she not only *keeps* them (easily taking 100 shots at a time!) but has to try to categorize them!

"Hmmm... a picture of a deer drinking from a stream. File that under wildlife, water and winter? Should I also file it under 'where taken'??"

So, its a tedious process. Esp when she decides she needs a new category and then wants to audit her previous sorts to move things out of less descriptive categories and into the new one(s) she's created.

Be like trying to sort databooks based on type of components:

"Hmmm... this one has memory, processors *and* generic logic! Which shelf do I put it on...?"

For aluminum? Not really. Depending on the material the little disk could be clogged in less than one minute. Aluminum need to be worked on more slowly, not with high RPM.

That's why I prefer my mountain bike. It allows me to travel via pristine areas where no cars can ever go. But after having busted two rear axles I really need a better one, 29-incher with full suspension. I just don't want to spend >$1k on it because it'll get beaten up.

[...]

Some of the old lenses are of remarkable quality.

[...]

I gave up on color inkjet printers. In summer the cartridges dry up, too expensive.

I don't like to have an extra reader box when there's already PCs and laptops. Mostly I connect the camera with the card inside, take a look and then delete really bad photos right then and there, on the card.

Then one day SWMBO uses the camera, turns it on ... "Now wait a minute, where did you photograph this flashy blonde here?!"

[...]

That would be the perfect application for a database. It's the same with my parts. I use many of them in unorthodox ways so they can't be sorted into digital and non-digital. I store them wherever there is suitable space and then enter P/N and location code into a database.

--
Regards, Joerg 

http://www.analogconsultants.com/

To say the least. I have been on standards committees, on and off, for

20 years or so. I have some experience there. Writing for clarity is more experience than anything else. There are things that help, but watching your work get misunderstood lots of times is the best teacher.

?-)