2 Basic Connection Requirements for Devices with MVIO

Multi-Voltage I/O requires that a voltage source always be connected to the VDDIOX supply pin(s). The MVIO supply can either be connected to the same voltage source as VDD, or it can be connected externally to an alternative source to achieve operation on a different voltage domain. MVIO pins can operate at a voltage level that is higher or lower than the main device VDD. However, it is important to refer to the electrical specifications section of the device data sheet to determine the operating conditions for each voltage domain.

The VDDIOx supply pins should be treated as standard VDD pins in hardware configuration. VDDIOx must always be connected during operation, and decoupling capacitors are required for each voltage domain. A 0.1 μF, 10-20V ceramic capacitor is recommended for each power supply pin, and in some applications, additional decoupling or tank capacitors may be necessary. Refer to the appropriate device data sheet for more detailed information. Figure 2-1 shows a simplified diagram of the recommended VDDIOx connections for PIC and AVR devices with MVIO.

Figure 2-1. Recommended VDDIOx Connections for Devices with MVIO
Tip: For systems that frequently cycle VDD or experience fast VDD transients, adding a decoupling capacitor (C3) if the power supply slew rate exceeds the slew rate limits of the device is recommended. Refer to the electrical specifications of the device data sheet for more information.