3 MVIO Power Supply Configuration Options
The VDDIOX power supply pin(s) can either be connected to their own independent voltage source or to the same source as VDD externally depending on the application. Most devices with MVIO have some configuration settings that can be used to optimize device performance when the same supply is being used for all domains. The MVIO module not only allows a subset of pins to be powered and operated from an alternative voltage domain, but it also has integrated hardware that is used for VDDIOx supply voltage monitoring. In applications where VDD and VDDIOx are connected to the same source, the standard VDD voltage monitoring systems can be used for both domains and the dedicated MVIO voltage monitoring circuitry can be disabled.
On most PIC device families with MVIO the VDDIOx voltage monitoring circuitry can be disabled by setting the IOMON bit of the VDDIOxCON register, which disables the I/O voltage monitoring circuits for the corresponding VDDIOX domain. On most AVR devices the MVIO voltage monitoring circuitry is disabled by configuring the MVIO module to operate in single supply mode instead of dual supply mode, using the MVSYSCFG (MVIO System Configuration) fuse. These MVIO options may vary from device to device, refer to the data sheet for more information.