7

7766DS–AVR–01/09

ATmega16U4/ATmega32U4

2.2.11

UVCC

USB Pads Internal Regulator Input supply voltage.

2.2.12

UCAP

USB Pads Internal Regulator Output supply voltage. Should be connected to an external capac-

itor (1µF).

2.2.13

VBUS

USB VBUS monitor input.

2.2.14

RESET

Reset input. A low level on this pin for longer than the minimum pulse length will generate a

2.2.15

XTAL1

Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.

2.2.16

XTAL2

Output from the inverting Oscillator amplifier.

2.2.17

AVCC

AVCC is the supply voltage pin (input) for all the A/D Converter channels. If the ADC is not used,

it should be externally connected to V

through a low-pass filter.

2.2.18

AREF

This is the analog reference pin (input) for the A/D Converter.