USB device protection/test adapter? - Page 1
Forum section: electronics / general

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:33:05 am
content: Is there anything like an adapter that connects between a USB device and whatever's upstream, protects both sides from frying (from whatever may be the cause), and that indicates overload/overvoltage/whatever conditions?

author: PeterG
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:36:32 am
content: I just got myself one of these, seems to work well enough for basic testing.http://www.ebay.com.au/itm/141028948395Regards

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:41:12 am
content: Interesting device. Does it flicker between voltage and current?Know of anything that shows max values too, and that provides protection as well?

author: PeterG
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:45:53 am
content: This is the only device like this i have found. It switched between voltage and current automatically about every 5 seconds or so.I actually got it to measure how much current devices are using while charging.Regards

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:53:25 am
content: Does it update the display also during each 5 second interval? If so, how fast?Maybe what's needed is an adapter with exposed lines you can hook a DMM to.But I wonder if it helps with protection...

author: PeterG
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:56:42 am
content: It seems to update about once a second.Regards

author: ve7xen
author_rank: Super Contributor
timestamp: March 21, 2014, 08:03:35 am
content: This doesn't appear to actually provide isolation, it's just a power supply (which is still handy). You're looking for something like this:https://www.olimex.com/Products/Modules/Interface/USB-ISO/

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 08:22:58 am
content: Peter, thanks.ve7xen: Thanks. That's an overkill for me, no high voltage is involved. I'm looking for a cheap and basic protection/error condition indication device for use between standard consumer USB host/client devices. The whole thing stems from me having fried a flash drive while trying anew USB hub.So I'm thinking, an adapter I can leave connected between a device and an upstream host. It'll provide protection, and indicate (even with something as basic as a LED) if an fault condition occurred since the adapter was connected.

author: ve7xen
author_rank: Super Contributor
timestamp: March 21, 2014, 10:20:07 am
content: Quote from: lpc32 on March 21, 2014, 08:22:58 amWell, without isolating the data lines there's not much in the way of protection going on, you're just providing a separate VBUS, which you hopefully trust. Any fault on the data lines will pass right through, as will ground loop currents etc. It's not about the isolation voltage spec, it's about fully isolating the DUT so there can be no fault currents to destroy things.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 03:19:27 pm
content: Maybe the device Peter suggested would provide some protection just because it's another device on the way, and the fact that some of them seem to be rated for >5V (if eBay specs are to be trusted). But yeah, probably nothing much there to protect D+/D-.

author: David_AVD
author_rank: Super Contributor
timestamp: March 21, 2014, 09:02:42 pm
content: Quote from: ve7xen on March 21, 2014, 08:03:35 amInterestingly it says "USB 2.0 Compliant" but only 12mb/s data rate, so it seems to be a USB 1.0 device. Still compatible with USB 2.0 ports of course, just not very fast.

author: ve7xen
author_rank: Super Contributor
timestamp: March 22, 2014, 12:18:57 am
content: USB 2.0 includes "Full Speed" and "High Speed" modes. You'll often see microcontrollers for example advertising USB 2.0 compatibility, but only supporting Full Speed mode. I'm not sure if anything relevant in the spec changed, but I think they're supposed to tell you which version of the spec the product was qualified against per the USB-IF.But yeah, it's a bit confusing.

author: ohmineer
author_rank: Contributor
timestamp: March 22, 2014, 10:35:21 am
content: I guess that Olimex device is based on Analog Devices' IC ADUM5000 and ADUM4160. There are some application notes in their website.Look for example at this app note:http://www.analog.com/static/imported-files/circuit_notes/CN0158.pdf.It does not seem too difficult to implement the circuit as a DIY practice if you want to do a first test on your USB devices.Here are the links to Analog Devices' website:http://www.analog.com/en/interface-isolation/digital-isolators/adum5000/products/product.htmlhttp://www.analog.com/en/interface-isolation/digital-isolators/adum4160/products/product.htmlI do not know how ADUM4160 works, but I have used ADUM5000 in the past and I am quite happy with the results.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 22, 2014, 11:47:53 am
content: Wouldn't something likeOn's NCP361orMaxim's MAX4987be more common?Looks like the data lines are usually just ESD protected (CM1213?). I wonder why.

author: ohmineer
author_rank: Contributor
timestamp: March 22, 2014, 12:15:30 pm
content: ESD protection on external connectors is fairly common. I would say it is a "must".An ESD event can occur either when you touch the device or when computer and device are plugged together due to the difference of charge between the parts.The energy of this event is potentially destructive, after all 15 kV peaks are not something that your small SMD packages can absorb easily.The drawback of ESD protectors is that you add capacitance to lines and this can have an effect on signal integrity.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 22, 2014, 01:00:20 pm
content: What I meant was, why only ESD protection for the data lines, and no overvoltage or whatever else. I suppose ESD is the common thing, but what about other potential faults?That CM1213 and other high-speed-oriented diodes have low capacitance.