capacitorusbusb hub
I'm looking at two different USB 2.0 hubs which both use the GL850. This is Hub 1:
(source: mydigit.net)
This is Hub 2:
(source: mydigit.net)
Both take an external power source but Hub 1 uses four 220uF caps. Does anyone know why a cap is used for each USB connector in Hub 1 but not in Hub 2?
It looks like you forgot the 15k pulldown termination resistors on DP[1-3] and DM[1-3], you can see these in the TUSB2036 datasheet in Figure 9 through 11. These resistors are part of the USB specification.
The USB signals can be connected directly to the Gumstix Overo USB connections. The easiest way to answer these type of questions is to look at the schematics for the Gumstix expansion boards, available here: http://pubs.gumstix.com/boards/ .
All these y splitters are, are a usb hub ic, a few passives, and the usb ports. It is an active device, not just wires. Some all in one USB hubs like GL850G are used. You could get a cheap dollar hub with one of those, then modify it as you want.
Best Answer
Here is the datasheet that includes the schematic for the GL850G SSOP28:
http://www.icpdf.com/GENESYS_datasheet/GL850G-SSOP28_pdf_8319365/GL850G-SSOP28_datasheet.html
The schematic is located on Page 2. The capacitors do indeed appear to be part of a filter between +5V and GND on the USB connectors.