As the title suggests, the design I'm taking over right now is USB1_VBUS enabled by 5V divider 3.3, with USB1 leading to a 3.0 Type-c connector for use;
USB2_VBUS is directly suspended and used by USB2 connected to a 3.0 HUB;
I found that USB2_VBUS dangling can also be used normally by connecting a USB flash drive through the HUB, this signal doesn't seem to be required to be pulled up;
My questions: 1. What is the actual purpose of this signal? Is it related to HOST/DEVICE?
2. If I change USB1 to direct connect HUB without using its OTG function can I also suspend USB1_VBUS?
1) This pin is the detection PIN for the 3.3V power rail. USBx_VBUS is the USB input signal used to detect the presence of an external 5V VBUS and to control the startup of the USB PHY and Host/Device selection.
Device/otg mode must be connected, after 30K to 5V, or after 1K to 3.3V. Without VBUS input, the controller cannot enter Device mode.
It can be left unconnected under Host, as you can see in our reference design
2) can be, but do not recommend USB1 to do HUB, usb1 to be used to do the download, design time to maintain functionality, debug the board is more convenient, refer to our reference design ha!