7.4 Multi-Voltage I/O

The target MCU includes a Multi-Voltage I/O (MVIO) domain powered through the VDDIO2 pin. Pins RC3–RC6 and RD0–RD7 are exclusively powered by VDDIO2. If VDDIO2 is not supplied, these I/O pins will not operate.

On the PIC18F56Q35 Curiosity Nano board, VCC_TARGET supplies VDDIO2 by default. Removing the 0Ω resistor R102 disconnects the default power connection. After removal, an external power supply can power the MVIO pins through the 1x2-100mil footprint (J100).

Warning:
  • Always disconnect the board from all power sources before making changes
  • To prevent damage to the board, remove R102 before applying external voltage to VDDIO2
  • The MVIO circuit lacks reverse polarity protection. Incorrect connections at J100 may permanently damage the board.
Figure 7-5. MVIO Block Diagram
Figure 7-6. VDDIO2 Connections