New USB2 isolation chip

[ajay_m]

I see now that apart from the ADUM3165-based devices, there is now a new TI chip, the ISOUSB211, for which some USB2 compatible isolators are starting to appear e.g

https://www.amazon.co.uk/Jhoinrch-Isola ... XN13EYXJQJ

and there are some similar, though more expensive units, which appear to have provision for external power (see below)

While I found the USB1.1 compatible ADUM3160-based isolators work fairly well, when I tried an ADUM3165-based device it was an abject failure, working only with a USB mouse, so I returned it. This new chip is allegedly technically better, in ways that involve nosebleedingly complex discussions of USB internals, so I don't know except to say I live in hope.... The USB 1.1 devices do work, but the limited bandwidth is an issue, so a USB2 isolator that actually worked well would be nice. Yes, there are the Topping devices, but they are quite expensive.

Haven't tried this one yet, might order one to check it out. Like the other units, it does have an annoyingly wide form factor, meaning you may need a short cable to interpose it and of course like all these adaptors, it's very limited in the downstream power it can supply, requiring that you splice in an isolated PSU downstream if you want to connect a bus-powered device that draws more than a couple of hundred milliamps. The units on Amazon with this chip in a larger box form factor (and costing a bit more) appear to have provision for external power, which might be convenient. USB isolators, if they can be made reliable, are a miracle cure for PC-based ground loops in my experience, and they have the huge advantage that, operating in the digital domain, they are not going to compromise signal integrity.

[Hugh Robjohns]

Useful to know. Thanks.

[Martin Walker]

Seconded - thanks ajay!

[resistorman]

Thanks, there were 2 on Amazon US, now just 1

[Martin Walker]

Thanks, there were 2 on Amazon US, now just 1

Excellent - do let us know if it successfully passes USB data up to 480Mbps for you.

[resistorman]

Thanks, there were 2 on Amazon US, now just 1

Excellent - do let us know if it successfully passes USB data up to 480Mbps for you.

Just got it delivered and did a quick test. Plugged an external T7 Shield drive directly to my computer's USB 3 A port and got a transfer rate of around 380Mbs. Put the isolater in between and got a solid 40Mbs. The same with a fast flash drive. The instructions say it's compatible with SOME drives, and to be fair my use case is to stop MIDI/ audio noise. Interestingly, the Waldorf Protein comes with something that looks a lot like this.

[ajay_m]

Mine arrived finally, bearing the proud brand 'Jhoinrch'. I have no idea how to pronounce that!. It lights up most prettily with a pink and gold pair of LEDs when connected. Despite claiming to provide 2W downstream power, (i.e 5V at 400mA) anything more than a thumb drive seemed not to work - an external SATA SSD and a small portable HDD powered by USB were not detected.

But a standard USB2 flash drive worked fine and Crystal disk speed test gave me 29MB/s serial transfer rate both through the isolator and directly connected, which seems to indicate that yes, it does indeed run at USB2 signalling speeds.

I have not yet had the time to make a special downstream cable where I can splice in a 5V phone charger. Using my handy 'dragon' USB power and voltage plugin thingy, the downstream voltage was around 4.9V with a thumb drive plugged in and 5.2V at the USB port directly, so it is a bit marginal on downstream power, but then, all these devices are. So the acid test will be whether it works with something that's not bus-powered - it DOES work with the Hydrasynth, I've just kicked off a backup and that seemed to work fine.

So a cautious thumbs-up at this stage.

[Hugh Robjohns]

Sounds promising