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| ATMEGA8U2_14 Datasheet, PDF (186/310 Pages) ATMEL Corporation – 125 Powerful Instructions – Most Single Clock Cycle Execution | |||
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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
VCC (V)
Max
Operating Frequency (MHz)
5.5
USB compliant,
4.5 with internal regulator
4.0
3.6
3.0
2.7
VCC min
0
USB compliant,
without internal regulator
USB not operational
16 MHz
8 MHz
2 MHz
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
VBUS
UDM
UDP
UVSS
VCC
AVCC
UCAP
1µF
UVCC
D+
D-
UVSS
VSS
XTAL1
XTAL2
7799DâAVRâ11/10
186
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