ATMEGA8U2-AUR Atmel, ATMEGA8U2-AUR Datasheet - Page 26

• Manufacturer Part Number: ATMEGA8U2-AUR
• Description: MCU AVR 8K FLASH 16MHZ 32TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8U2-AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-TQFP, 32-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -

8. System Clock and Clock Options
8.1
8.1.1
8.1.2
8.1.3
7799D–AVR–11/10
Clock Systems and their Distribution
CPU Clock – clk
I/O Clock – clk
Flash Clock – clk
I/O
Figure 8-1
need not be active at a given time. In order to reduce power consumption, the clocks to modules
not being used can be halted by using different sleep modes, as described in
ment and Sleep Modes” on page
Figure 8-1.
The CPU clock is routed to parts of the system concerned with operation of the AVR core.
Examples of such modules are the General Purpose Register File, the Status Register and the
data memory holding the Stack Pointer. Halting the CPU clock inhibits the core from performing
general operations and calculations.
The I/O clock is used by the majority of the I/O modules, like Timer/Counters, SPI, and USART.
The I/O clock is also used by the External Interrupt module, but note that some external inter-
rupts are detected by asynchronous logic, allowing such interrupts to be detected even if the I/O
clock is halted.
The Flash clock controls operation of the Flash interface. The Flash clock is usually active simul-
taneously with the CPU clock.
CPU
FLASH
PLL Clock
Prescaler
USB PLL
USB
X6
clk
clk
presents the principal clock systems in the AVR and their distribution. All of the clocks
clk
Pllin (8MHz)
USB (48MHz)
XTAL (2-16 MHz)
Clock Distribution
Oscillator
Crystal
General I/O
Modules
42. The clock systems are detailed below.
clk
I/O
System Clock
Control Unit
AVR Clock
Multiplexer
Prescaler
External
Clock
Clock
Source clock
ATmega8U2/16U2/32U2
CPU Core
clk
clk
Reset Logic
CPU
FLASH
Watchdog clock
Watchdog Timer
RAM
Watchdog
Oscillator
“Power Manage-
Calibrated RC
Flash and
EEPROM
Oscillator
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