ATMEGA645-16MU Atmel, ATMEGA645-16MU Datasheet - Page 31

• Manufacturer Part Number: ATMEGA645-16MU
• Description: IC AVR MCU FLASH 64K 64-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA645-16MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• 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): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-MLF®, 64-QFN
• Processor Series: ATMEGA64x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: SPI, UART, USI
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 54
• Number Of Timers: 3
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• Package: 64MLF EP
• Device Core: AVR
• Family Name: ATmega
• Maximum Speed: 16 MHz
• For Use With: ATSTK600-TQFP64 - STK600 SOCKET/ADAPTER 64-TQFP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.7
8.8
2570M–AVR–04/11
Clock Output Buffer
Timer/Counter Oscillator
Figure 8-3.
When this clock source is selected, start-up times are determined by the SUT Fuses as shown in
Table 8-10 on page
Table 8-10.
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. It is required to ensure that the
MCU is kept in Reset during such changes in the clock frequency.
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
32
When the CKOUT Fuse is programmed, the system Clock will be output on CLKO. This mode is
suitable when the chip clock is used to drive other circuits on the system. The clock will be out-
put also during reset and the normal operation of I/O pin will be overridden when the fuse is
programmed. Any clock source, including internal RC Oscillator, can be selected when CLKO
serves as clock output. If the System Clock Prescaler is used, it is the divided system clock that
is output when the CKOUT Fuse is programmed.
Atmel ATmega325/3250/645/6450 share the Timer/Counter Oscillator Pins (TOSC1 and
TOSC2) with XTAL1 and XTAL2. This means that the Timer/Counter Oscillator can only be used
when the calibrated internal RC Oscillator is selected as system clock source. The Oscillator is
optimized for use with a 32.768kHz watch crystal. See
connection.
SUT1..0
for details.
00
01
10
11
Start-up Time from Power-
down and Power-save
External Clock Drive Configuration
Start-up Times for the External Clock Selection
31.
6 CK
6 CK
6 CK
EXTERNAL
SIGNAL
CLOCK
NC
Additional Delay from
Reset (V
Reserved
ATmega325/3250/645/6450
14CK + 4.1ms
14CK + 65ms
14CK
CC
= 5.0V)
XTAL2
XTAL1
GND
Figure 8-2 on page 28
“System Clock Prescaler” on page
BOD enabled
Fast rising power
Recommended Usage
Slowly rising power
for crystal
31