Hi;
I make a pcb with tusb2036 and two usb outs, like schematic:
http://www.flickr.com/photos/falcosms/
the power supply is externall, so i put the /buspwr in low, like datasheet say, /ocprot and /overcur in high, for not overcurrent detection, mode in low, for crystal use.
but, if /buspwr in low, when i connetc the board in PC and put a pen driver - for example, in the usb port (CN7), the windows xp show me the message "usb power exceeded".
if i power off the circuit, put the /buspwr in high and power on, the circuit works.
i am wrong in my understanding? this pin should be put in low to work correctly?
i make another board with tusb2046 - see schematic 2046-1, this board works fine, with externall power supply too and pin /busspwr in low.
whay this difference between two hubs?
yours trully
marcelo
Hello Marcelo,
The functionality of the terminal BUSPWR is reversed between the TUSB2036 and the TUSB2046B.
On the TUSB2036 this terminal is active-low, so if you are using an external source for the device you should tie this terminal to 3.3V.
On the TUSB2046B this terminal is active-high, so if you are using an external source you should tie this terminal to ground.
Regards.