I am a new logic hobbyist. This is a USB switch I am trying to build. I want to share my keyboard between two computers and be able to switch between them by clicking on SW1. The keyboard will be connected to the USB connector on the bottom, and the two USB's on the RHS to each computer. It will be great to hear the expert's opinion on this before I go ahead and order parts.
Update: Uploaded a new Fig. Please find the links to the devices blow:
- NAND: http://www.mouser.com/ds/2/405/cd4011b-404423.pdf
- TS3: http://www.ti.com/lit/ds/symlink/ts3usb30e.pdf
- GF1: http://www.mouser.com/ds/2/149/GF1A-188833.pdf
Best Answer
If you look at the datasheet of TS3USB30E that you're using, it only supports 3 V to 4.3 V for its own power supply (Vcc). So not only is connecting the VBUS'es of two computers together a bad idea (as @jippie noted), but you'll all supply 5V to your TS3's Vcc via Vdd (on your schematic).
I suspect they've spec'd the TS3 that way so that you can power it with a diode drop from 5V via diode ORing from two sources. Alas there's not much in the way of suggested application info in that datasheet.