AT90USB647-MU Atmel, AT90USB647-MU Datasheet - Page 39

• Manufacturer Part Number: AT90USB647-MU
• Description: MCU, 8BIT, 64K FLASH, USB, 64QFN
• Manufacturer: Atmel

Specifications of AT90USB647-MU

• Controller Family/series: AT90
• No. Of I/o's: 48
• Eeprom Memory Size: 2KB
• Ram Memory Size: 4KB
• Cpu Speed: 16MHz
• No. Of: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 64KB
• Oscillator Type: External, Internal
• Package: 64QFN EP
• Device Core: AVR
• Family Name: AT90
• Maximum Speed: 20 MHz
• Ram Size: 4 KB
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 8 Bit
• Program Memory Type: Flash
• Number Of Programmable I/os: 48
• Interface Type: SPI/TWI/USART/USB
• On-chip Adc: 8-chx10-bit
• Operating Temperature: -40 to 85 °C
• Number Of Timers: 4
• Lead Free Status / Rohs Status: Details

6. System Clock and Clock Options
6.1
6.1.1
6.1.2
6.1.3
7593K–AVR–11/09
Clock Systems and their Distribution
CPU Clock – clk
I/O Clock – clk
Flash Clock – clk
I/O
Figure 6-1
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 6-1.
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. Also, TWI address recognition is handled in all sleep modes.
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
USB PLL
Prescaler
USB
presents the principal clock systems in the AVR and their distribution. All of the clocks
X24
clk
clk
Pllin (2MHz)
USB (48MHz)
Clock Distribution
Asynchronous
Timer/Counter
Timer/Counter
Oscillator
51. The clock systems are detailed below.
General I/O
Modules
clk
clk
ASY
Oscillator
I/O
Crystal
Source clock
System Clock
Control Unit
AVR Clock
Multiplexer
Prescaler
Clock
ADC
External Clock
clk
ADC
CPU Core
clk
clk
Reset Logic
CPU
FLASH
AT90USB64/128
Watchdog clock
Watchdog
Oscillator
Watchdog Timer
RAM
“Power Manage-
Calibrated RC
Flash and
EEPROM
Oscillator
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