I've been looking through STM32 development board circuits to find the best way to connect the USB disconnect. I found the above circuit from the STM3210E-EVAL board, but all of the ST boards appear to have similar layouts. I have a couple questions about this layout:
- Why are there two transistors? Why isn't T2 sufficient?
- Why are there transistors at all? Could USB_DP be connected to a GPIO via a resistor and toggle between floating and on?
- If not 2, could a P-CH MOSFET with a low VGS be used instead?