ATmega325 Atmel Corporation, ATmega325 Datasheet - Page 29

• Manufacturer Part Number: ATmega325
• Manufacturer: Atmel Corporation

Specifications of ATmega325

• Flash (kbytes): 32 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 54
• Ext Interrupts: 17
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 1024
• 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: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

9.4
9.5
2570N–AVR–05/11
Low-frequency Crystal Oscillator
Calibrated Internal RC Oscillator
Table 9-4.
Note:
To use a 32.768 kHz watch crystal as the clock source for the device, the low-frequency crystal
Oscillator must be selected by setting the CKSEL Fuses to “0110” or “0111”. The crystal should
be connected as shown in
are determined by the SUT Fuses as shown in
in
Table 9-5.
Table 9-6.
Note:
The calibrated Internal RC Oscillator by default provides a 8.0MHz clock. The frequency is nom-
inal value at 3V and 25°C. The device is shipped with the CKDIV8 Fuse programmed. See
“System Clock Prescaler” on page 32
CKSEL0
CKSEL3..0
SUT1..0
0110
Table 9-6 on page
00
01
10
11
0111
0
1
1
1
1
(Note:)
1. These options should only be used when not operating close to the maximum frequency of the
2. These options are intended for use with ceramic resonators and will ensure frequency stability
This option should only be used if frequency stability at start-up is not important for the application
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
SUT1:0
Additional Delay from Reset (V
Start-up Times for the Crystal Oscillator Clock Selection (Continued)
Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
11
00
01
10
11
29.
Power-down and Power-save
Start-up Time from
Power-down and
14CK + 4.1ms
14CK + 65ms
Figure 9-2 on page
Power-save
Start-up Time from
1K CK
1K CK
16K CK
16K CK
16K CK
14CK
32K CK
1K CK
(2)
(2)
for more details.
CC
Reserved
ATmega325/3250/645/6450
= 5.0V)
28. When this Oscillator is selected, start-up times
Additional Delay
Table 9-5 on page 29
14CK + 4.1ms
14CK + 4.1ms
14CK + 65ms
14CK + 65ms
(V
from Reset
CC
14CK
= 5.0V)
Recommended Usage
Fast rising power or BOD enabled
Slowly rising power
Stable frequency at start-up
Recommended Usage
Stable frequency at start-up
Recommended
Usage
Ceramic resonator,
fast rising power
Ceramic resonator,
slowly rising power
Crystal Oscillator,
BOD enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator,
slowly rising power
and CKSEL1..0 as shown
29