[Solved / Archived] Zero4U: USB Hubs dying after two or three uses

We have never seen a case that the chip gets damaged by normal usage.

How do you use the Zero4U board? I mean more specific information. Such as:

• how do you power the Zero4U board
• how do you connect Zero4U board to host computer
• what is the host computer and what OS is running on it
• what USB device have you connected to your Zero4U board

Power: we use a MURATA 1.5A  switching power module on a PCB, the Zero4U module is soldered to our PCB - we use the Pogopin holes and use silver-wire instead

The host computer is internally connected with a Molex-cable, which is more or less fix installed.

Our system is using Linux, but that is not the problem. It behaves the same on windows or linux

The USB device is a typical usb stick, we have several customer complaints about dying USB ports, and from different companies. So the brand of the stick seems not to matter.

@wet Zero4U as a product has been in the market for over 8 years, and its circuit design has no change since then. The problem is not likely from our design but rather from the way to use it.

I can only suggest to check again these aspects:

• The actual voltage you feed to Zero4U board should be within standard (5V +- 5%).
• The D- and D+ trace on your carrier board should be properly routed (differential pair with 90 Ohms impedance, length matched, with ground copper aside and ground copper panel on the other side of PCB).
• using a Molex-cable to connect to the up-stream (host computer) may not be a good idea, especially when the cable lenth is rather long. The signal integrity may be broken and too much failures and retires may also overload the chip.

We have a suspicion that ESD might destroy the chip/module. We tried to analyze the Zero4U and we see no protection against it (in the upstream USB). Do you think that it might help that we add some ESD protection diodes on our board?

Would it help to send you one of our defective modules, so you can analyze them?

Normally ESD tests are part of the CE tests our lab makes - what kind of tests have you run?

@wet When you use Zero4U board as a module in your own product, you are the one who make sure the whole system running as expected. We didn't advertise that Zero4U can work under any circumstances. 

There is no ESD protection on Zero4U board -- it can not be done without using much smaller components and significently increasing the cost. Also I can't tell whether adding ESD protection can solve the problem - you need to figure out the root cause first.

Posted by: @wet

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Would it help to send you one of our defective modules, so you can analyze them?

No. We will not work on this issue, because the way you use Zero4U board is very different than the way we expected. You can of course use it like that, but it is also your job to diagnose such issue.