ATmega8U2/16U2/32U2
20.3 USB Module Powering Options
Depending on the selected target application power supply (VCC), the ATmega8U2/16U2/32U2
USB controller requires different powering schemes, see Figure 20-2 on page 186.
Figure 20-2. Operating modes versus frequency and power-supply
Max
VCC (V)
Operating Frequency (MHz)
5.5
16 MHz
USB compliant,
with internal regulator
4.5
4.0
3.6
8 MHz
USB compliant,
without internal regulator
3.0
2.7
USB not operational
2 MHz
VCC min
0
20.3.1
Bus Powered device
The following figures show typical implementations for different powering schemes.
Figure 20-3. Typical Bus powered application with 5V I/O
VCC
AVCC
UCAP
1µF
VBUS
UDM
UDP
UVCC
D+
D-
UVSS
UVSS
VSS
XTAL1
XTAL2
186
7799D–AVR–11/10
ATMEL [ ATMEL ]
