The AT43312A is a 5 port USB hub chip supporting one upstream and four downstream ports. The AT43312A connects to an upstream hub or Host/Root Hub via Port0 and the other ports connect to external downstream USB devices. The hub re-transmits the USB differential signal between Port0 and Ports[1:4] in both directions. A USB hub with the AT43312A can operate as a bus-powered or self-powered through chip's power mode configuration pin. In the self-powered mode, port power can be switched or unswitched. Overcurrent reporting and port power control can be individual or global. An on-chip power supply eliminates the need for an external 3.3V supply.