1.2.1 Power Options
The MCP2222 supports the following power configurations:
- USB bus-powered operation with 5V or derived 3.3V
- Self-powered operation with a 3.3V or 5V supply
The MCP2222 includes an internal 3.3V Low-Dropout (LDO) regulator that powers the USB transceiver and DP/DM pins when the VDD voltage is 5V. When the VDD voltage is 3.3V, the LDO is switched off, and a 3.3V supply must be connected externally to the VUSB pin to power the USB transceiver.
The device is held in the Reset state when the voltage on the VDD pin is below 2.85V.
The MCP2222 device can be powered using the USB bus power or any available 3.3V or 5V
system rail. The voltage applied to VDD determines the voltage levels on the
I/O pins, as well as on the UART, I2C, and SPI pins. When VDD is
5V, all these pins will have a logical ‘1’ of approximately 5V, with
the variations specified in the DC Characteristics section.
Although USB provides a 5V bus supply, the USB transceiver requires 3.3V for signaling on the DM and DP lines. The voltage on the DM and DP pins depends on the voltage of the VUSB pin. If VDD is greater or equal to 5V, the internal 3.3V LDO regulator is enabled and provides 3.3V to the VUSB pin. In this case, a bypass capacitor must be connected externally to the VUSB pin. If VDD is 3.3V, a 3.3V supply must be connected externally to the VUSB pin.
USB 2.0 devices are required to support Low-Power Suspend mode. During USB Suspend mode, devices must limit current consumption from the 5V USB BUS to no more than 500 μA (or 2.5 mA for high-powered devices that are remote wake-up capable).
The USB host places a USB device in Suspend mode by stopping USB traffic to that device for more than 3 ms.