The ISP1161 is a single-chip Universal Serial Bus (USB) Host Controller (HC) and Device Controller (DC) which complies with Universal Serial Bus Specification Rev 1.1. These two USB controllers, the HC and the DC, share the same microprocessor bus interface. They have the same data bus, but different I/O locations. They also have separate interrupt request output pins, separate DMA channels that include separate DMA request output pins and DMA acknowledge input pins. This makes it possible for a microprocessor to control both the USB HC and the USB DC at the same time. ISP1161 provides two downstream ports for the USB HC and one upstream port for the USB DC. Each downstream port has its own overcurrent (OC) detection input pin and power supply switching control output pin. The upstream port has its own VBUS detection input pin. ISP1161 also provides separate wakeup input pins and suspended status output pins for the USB HC and the USB DC, respectively. This makes power management flexible. The downstream ports for the HC can be connected with any USB compliant USB devices and USB hubs that have USB upstream ports. The upstream port for the DC can be connected to any USB compliant USB host and USB hubs that have USB downstream ports. c