1

The fastest isolators available a a reasonable cost are 150 Mbps per channel. High Speed USB has a data rate of 480 Mbps. So how do you isolate a HS USB?

The first thing that comes to mind is to somehow convert the serial stream into n parallel streams which run at about 480/n Mbps each and then send these parallel streams over the available isolators and convert it back to serial on other side. I'm sure this is not as easy as it sounds.

I have seen some expensive looking FPGA based designs that do this. Since it can be done using an FPGA, I wonder why no semiconductor company is providing a ready to use 480 Mbps USB isolator. This approach looks so scalable that even higher rates could be possible.

Dojo
  • 919
  • 10
  • 19
  • *The fastest* **violators** *available a*, you mean isolators I guess. *I wonder why no semiconductor company is providing* Obviously there are alternative solutions (which you mention) and/or there is not sufficient demand to design such a dedicated chip. It can cost millions to develop and market a chip so semiconductor companies want to be quite sure there's a demand for a certain chip before they are going to make it. – Bimpelrekkie Oct 07 '18 at 10:08
  • 1
    First question is why do you want to isolate the USB port as opposed to whatever the USB device connects to? Remember it was only originally designed to provide a link between a computer and a bunch of peripherals within close range. – Finbarr Oct 07 '18 at 11:21
  • A quick search reveals products from Intona Technology, Coolgear, Advantech, HiFimeDIY, among others. – Dave Tweed Oct 07 '18 at 14:31
  • @Bimpelrekkie Yes, I totally meant isolators. Chrome's spellcheck suggests violators when you type isolators. Guess I wasn't paying attention when selecting the correction :) Hmm, I think I have seen pretty esoteric ICs being churned out. USB is a mass market protocol, if you build it they will come. – Dojo Oct 07 '18 at 18:56
  • @Finbarr 1. It is not a either this or that choice. Some applications don't need a isolator, but mistakes like shorting something, connecting the wires wrong etc do happen during development so you need a last piece of protection between the DUT and the computer. USB is usually how you connect to the computer so if you have a USB isolator, it can be used for all projects. The individual devices may or may not have isolation as per their intended end use. – Dojo Oct 07 '18 at 19:09
  • Sometimes its the device that you want to shield and not the computer. I have seen cases where the noise from a laptop charger affected the DUT to the extent that I had to turn off the charger to be able to work with the device. Ya, you could put isolators in the DUT but devices are designed for their end application and not for testing convince. – Dojo Oct 07 '18 at 19:16

0 Answers0