1.2.2 Powering the MCP2222 With USB Bus Power (5V Supply)
In USB bus-powered operation, application power is supplied from the USB bus. This is the simplest power configuration for the MCP2222.
To meet USB 2.0 inrush current requirements, the total effective capacitance appearing across VBUS and ground must not exceed 10 μF. If the capacitance exceeds this value, an inrush current-limiting circuit is required. Refer to the latest “Universal Serial Bus Specification” for additional information on limiting inrush current.
During USB Suspend mode, the DP or DM pull-up resistor must remain active, which contributes to the allowable suspend current budget (500 μA or 2.5 mA). The VUSB pin requires an external ceramic bypass capacitor with a value between 0.22 and 0.47 μF.
To power the device with 5V USB bus supply, the VBUS supply from the USB receptacle is connected directly, or through a start-up delay circuit, to the VDD pin. The nominal 5V VBUS supply powers the device, and the internal 3.3V regulator powers the USB transceiver.
Figure 1-1 below shows a typical circuit in which the MCP2222 is powered from USB bus power and its internal LDO supplies 3.3V to the USB transceiver. When the internal LDO is used, a capacitor must be connected to the VUSB pin.
