ATMEGA644V-10MUR Atmel, ATMEGA644V-10MUR Datasheet - Page 35

• Manufacturer Part Number: ATMEGA644V-10MUR
• Description: MCU AVR 64K FLASH 10MHZ 44QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644V-10MUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 10MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7.8
2593N–AVR–07/10
External Clock
To drive the device from an external clock source, XTAL1 should be driven as shown in
7-3. To run the device on an external clock, the CKSEL Fuses must be programmed to “0000”.
Figure 7-3.
When this clock source is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 7-12.
Table 7-13.
When applying an external clock, it is required to avoid sudden changes in the applied clock fre-
quency to ensure stable operation of the MCU. A variation in frequency of more than 2% from
one clock cycle to the next can lead to unpredictable behavior. If changes of more than 2% is
required, ensure that the MCU is kept in Reset during the changes.
Note that the System Clock Prescaler can be used to implement run-time changes of the internal
clock frequency while still ensuring stable operation. Refer to
36
BOD enabled
Fast rising power
Slowly rising power
for details.
Power Conditions
7-13.
External Clock Drive Configuration
Crystal Oscillator Clock Frequency
Start-up Times for the External Clock Selection
Nominal Frequency
0 - 20 MHz
EXTERNAL
SIGNAL
CLOCK
Start-up Time from Power-
down and Power-save
NC
Reserved
6 CK
6 CK
6 CK
XTAL2
XTAL1
GND
Additional Delay from
”System Clock Prescaler” on page
Reset (V
14CK + 4.1 ms
14CK + 65 ms
14CK
CC
ATmega644
CKSEL3..0
= 5.0V)
0000
SUT1..0
00
01
10
11
Figure
35