No USB ESD protection?

Question

No USB ESD protection?

mkschreder opened this issue 7 years ago · 4 comments

Hello,

Is there no USB ESD protection on any of the olinuxino boards? I have looked at a few schematics and I could not find it. Is it usually built into the Allwinner soc?

Answer 1 · 2018-03-21T06:13:29.000Z

USB cables and connector are grounded and this eliminates some of the ESD. There is no separate ESD protection for the USB ports. Additional IC or Zener diodes can be placed if somebody frequently has such problems. The main reason for the lack of such protection is that we haven't encountered ESD problems with the USBs and complicating the schematics further sometimes leads to more problems.

Answer 2 · 2018-03-21T07:21:36.000Z

this means you can not such boards EC - compliant. the devices for home and office use should withstand short bipolar pulses with 500V peak voltage, 50 us length (1.2 us front time, 20us down to half value), applied between line and ground for any power or signal pin on any connector. for the industrial devices line-to-line testing may be needed as well.

Answer 3 · 2018-03-21T07:59:48.000Z

Kinda hard to place extra diodes if it is a full board and not a som that plugs into a custom carrier. I also second the point about EC compliance. Good news is we can always just redesign the schematic and make our own versions. Thanks!

Answer 4 · 2018-03-21T08:33:53.000Z

We have Allwinner SOM boards and you can use the open design of the evaluation boards compatible with the SOMs to tailor the USB circuit as you might like:

A20-SOM: https://www.olimex.com/Products/SOM/A20/A20-SOM/
A20-SOM204: https://www.olimex.com/Products/SOM204/A20/A20-SOM204/
A13-SOM-256: https://www.olimex.com/Products/SOM/A13/A13-SOM-256/
A13-SOM-512: https://www.olimex.com/Products/SOM/A13/A13-SOM-512/