ATmega1280 Atmel Corporation, ATmega1280 Datasheet - Page 48

• Manufacturer Part Number: ATmega1280
• Manufacturer: Atmel Corporation

Specifications of ATmega1280

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 86
• Ext Interrupts: 32
• Usb Speed: No
• Usb Interface: No
• Spi: 5
• Twi (i2c): 1
• Uart: 4
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 16
• Input Capture Channels: 4
• Pwm Channels: 15
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

10.9
2549N–AVR–05/11
External Clock
When this clock source is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 10-12. Start-up Times for the 128kHz Internal Oscillator
To drive the device from an external clock source, XTAL1 should be driven as shown in
10-4. To run the device on an external clock, the CKSEL Fuses must be programmed to “0000”.
Figure 10-4. External Clock Drive Configuration
When this clock source is selected, start-up times are determined by the SUT Fuses as shown in
Table 10-15 on page
Table 10-13. Crystal Oscillator Clock Frequency
Table 10-14. Start-up Times for the External Clock Selection
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.
Slowly rising power
Slowly rising power
Power Conditions
Power Conditions
Fast rising power
Fast rising power
10-12.
BOD enabled
BOD enabled
Nominal Frequency
51.
0 - 16MHz
EXTERNAL
Start-up Time from Power-
Start-up Time from Power-
SIGNAL
CLOCK
down and Power-save
down and Power-save
ATmega640/1280/1281/2560/2561
NC
Reserved
Reserved
6CK
6CK
6CK
6CK
6CK
6CK
XTAL2
XTAL1
GND
Additional Delay from
Additional Delay from
Reset (V
14CK + 4.1ms
14CK + 64ms
14CK + 65ms
14CK + 4ms
Reset
14CK
14CK
CC
CKSEL3:0
= 5.0V)
0000
SUT1:0
SUT1:0
00
01
10
11
Figure
00
01
10
11
48