All LPC2400 series and some members of the LPC2300 series support USB Host and On The Go (OTG). The USB Host function allows the MCU to interface with USB devices attached to the bus. This function features two downstream ports, supports per-port power switching, and doesn’t require an external PHY. The USB OTG functionality integrates the host and device controller while the dedicated I2C interface controls any external OTG PHY compliance with the OTG transceiver specification. USB OTG supports any OTG transceiver that is compliant with the OTG transceiver specification in the USB 2.0 specification.