1.2.3 Powering the MCP2222 Using USB Bus Power With an External 3.3V Regulator
Some applications require a 3.3V supply for their devices. To derive 3.3V from the USB bus, an external 3.3V regulator must be used.
To power the MCP2222 with 3.3V derived from USB bus power, the VBUS supply from the USB receptacle must be connected directly, or through a start-up delay circuit, to the input of an external 3.3V regulator. The regulator output is connected to the MCP2222 VDD pin.
In this configuration, the VUSB pin must also be externally connected to a 3.3V supply to provide 3.3V to the USB transceiver.
