ATMEGA644A-PU Atmel, ATMEGA644A-PU Datasheet - Page 334

• Manufacturer Part Number: ATMEGA644A-PU
• Description: IC MCU AVR 64K FLASH 40PDIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644A-PU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• 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: 40-DIP (0.600", 15.24mm)
• Processor Series: ATmega
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: JTAG, TWI, SPI, USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

27.3
Table 27-10. Calibration Accuracy of Internal RC Oscillator
Notes:
27.3.1
27.3.2
Table 27-11. External Clock Drive
8272A–AVR–01/10
Factory
Calibration
User
Calibration
Symbol
1/t
t
t
t
t
t
Δ
CLCL
CHCX
CLCX
CLCH
CHCL
t
CLCL
CLCL
Clock Characteristics
1. Voltage range for ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P.
External Clock Drive Waveforms
External Clock Drive
Parameter
Oscillator Frequency
Clock Period
High Time
Low Time
Rise Time
Fall Time
Change in period from one
clock cycle to the next
Figure 27-2. External Clock Drive Waveforms
164A/164PA/324A/324PA/644A/644PA/1284/1284P
7.3 - 8.1 MHz
Frequency
8.0 MHz
V
Min.
IL1
250
100
100
V
0
CC
V
IH1
=1.8 - 5.5V
1.8V - 5.5V
Max.
2.0
2.0
4
2
V
3V
CC
(1)
Min.
100
40
40
V
0
CC
=2.7 - 5.5V
Max.
Temperature
-40°C - 85°C
1.6
1.6
10
2
25°C
Min.
50
20
20
V
0
CC
=4.5 - 5.5V
Calibration Accuracy
Max.
0.5
0.5
20
2
±10%
±1%
Units
MHz
ns
ns
ns
μs
μs
%
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