I have a device that can take power in from two USB ports. I want to make sure that when the USB2 is plugged in, the USB1 Power gets disconnected. I have come up with the following schematic design for this purpose.
- When USB2 is plugged in, the PMOS turns off and USB1 power disconnects
- When USB2 is not plugged in, the PMOS turns on and USB1 power connects
- When both USB1 and USB2 are connected, only USB2 sources power but USB1 can be used for communication only
Am I doing it right?
On side note,
a. The Schottky Power Rectifier has a forward voltage of 0.375 and 0.4V. Are there ways to get rid of the diodes and place a transistor instead? b. The PMOS has a minimum required Vgs of -0.4V. What does the negative symbol means?