ATMEGA645P-MUR Atmel, ATMEGA645P-MUR Datasheet - Page 138

• Manufacturer Part Number: ATMEGA645P-MUR
• Description: MCU AVR 64KB FLASH 16MHZ 64QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA645P-MUR

• 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: 54
• 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: 64-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/645
Each half period of the external clock applied must be longer than one system clock cycle to
ensure correct sampling. The external clock must be guaranteed to have less than half the sys-
tem clock frequency (f
sampling, the maximum frequency of an external clock it can detect is half the sampling fre-
quency (Nyquist sampling theorem). However, due to variation of the system clock frequency
and duty cycle caused by Oscillator source (crystal, resonator, and capacitors) tolerances, it is
recommended that maximum frequency of an external clock source is less than f
An external clock source can not be prescaled.
Figure 16-2. Prescaler for Timer/Counter0 and Timer/Counter1
Note:
PSR10
clk
T0
T1
I/O
1. The synchronization logic on the input pins (
Synchronization
Synchronization
ExtClk
< f
clk_I/O
/2) given a 50/50% duty cycle. Since the edge detector uses
clk
Clear
T1
T1/T0)
is shown in
(1)
Figure
16-1.
clk
T0
clk_I/O
8285B–AVR–03/11
/2.5.