ATmega325P Atmel Corporation, ATmega325P Datasheet - Page 34

• Manufacturer Part Number: ATmega325P
• Manufacturer: Atmel Corporation

Specifications of ATmega325P

• Flash (kbytes): 32 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 20 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: Yes
• 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

8.7
34
External Clock
ATmega325P/3250P
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table 8-9 on page
Table 8-9.
Note:
To drive the device from an external clock source, XTAL1 should be driven as shown in
3. To run the device on an external clock, the CKSEL Fuses must be programmed to “0000”.
Figure 3. External Clock Drive Configuration
When this clock source is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 1. Crystal Oscillator Clock Frequency
Table 2. 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
Power Conditions
BOD enabled
Fast rising power
Slowly rising power
CKSEL3..0
0000
SUT1..0
00
01
10
11
2.
1. The device is shipped with this option selected
Start-up Time from Power-
Start-up times for the internal calibrated RC Oscillator clock selection
down and Power-save
34.
6 CK
6 CK
6 CK
EXTERNAL
SIGNAL
CLOCK
Start-up Time from Power-
down and Power-save
NC
Reserved
Frequency Range
0 - 16 MHz
6 CK
6 CK
6 CK
Additional Delay from
Reset (V
Reserved
14CK + 4.1 ms
14CK + 65 ms
.
XTAL2
XTAL1
GND
14CK
CC
= 5.0V)
Additional Delay from
Reset (V
14CK + 65 ms
14CK + 4.1 ms
14CK
CC
BOD enabled
Fast rising power
Slowly rising power
Recommended Usage
= 5.0V)
(1)
8023F–AVR–07/09
SUT1..0
00
01
10
11
Figure