After killing two of my desktop PC’s USB ports during development I wanted to be more careful with the remaining few. I considered rolling my own hub with 4 isolated downstream ports. But after a quick search for the parts I’d need, such as a few USB isolator IC’s, a few 3W dc/dc converters and a USB hub ic with all the mechanical parts required to make it robust, it was going to be an expensive project.
I went looking for USB hubs, and the only one to be for sale in Europe without “call-us” price was the B&B Electronics UHR304. I couldn’t find any info regarding what was inside, and I was afraid I’d buy an cheap USB hub in a fancy metal enclosure. But I wanted to save my precious USB ports on my pc, so I bought one.
Since there are no teardown images to be found online to estimate the quality, here they are! (highres link below)
I was surprised by the amount of components inside, sure looks high quality. Some of the features are:
- Significant TVS diodes on the power supply inputs.
- Common mode filter on power input and USB downstream data.
- The screws connect to earth via 0 ohm resistors.
- Reverse polarity protection for the DC barrel.
- Analog Devices ADUM4160 USB 1.1 Isolator for the upstream port (no power).
- Texas Instruments LM22676 buck converter.
- National Semiconductor LM2937 LDO for the logic, I guess.
- Micrel MIC2026 power switchers with overload protection.
- ST USBLC6-2SC6 ESD protection on all USB ports.
- And last but not least, an SMSC (microchip) USB2514Bi USB Hub Controller protection on all USB ports.
I paid €130 on eBay for a new one, which is a lot for “just a USB Hub”. But considering that if I made my own, which would cost over 300 and would have almost identical parts in it with a less fancy enclosure, I sure am happy to know that my USB ports now remain safe from all the accidents that happen downstream on my bench, that would normally fry a USB port.
I know the ADUM4160 is available in small USB Isolated sticks for €50, but these do not offer the full 2.5W of power delivery, which limits development to self-powered devices, unless I make a power insertion cable/board. They also don’t mount on the desk as fancy as this does.