ATmega8 Atmel Corporation, ATmega8 Datasheet - Page 30

• Manufacturer Part Number: ATmega8
• Manufacturer: Atmel Corporation

Specifications of ATmega8

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 2
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• 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): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Calibrated Internal
RC Oscillator
30
ATmega8(L)
The calibrated internal RC Oscillator provides a fixed 1.0MHz, 2.0MHz, 4.0MHz, or 8.0MHz
clock. All frequencies are nominal values at 5V and 25°C. This clock may be selected as the
system clock by programming the CKSEL Fuses as shown in
with no external components. The CKOPT Fuse should always be unprogrammed when using
this clock option. During reset, hardware loads the 1MHz calibration byte into the OSCCAL Reg-
ister and thereby automatically calibrates the RC Oscillator. At 5V, 25°C and 1.0MHz Oscillator
frequency selected, this calibration gives a frequency within ±3% of the nominal frequency.
Using run-time calibration methods as described in application notes available at
www.atmel.com/avr it is possible to achieve ±1% accuracy at any given V
When this Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the
Watchdog Timer and for the Reset Time-out. For more information on the pre-programmed cali-
bration value, see the section
Table 9. Internal Calibrated RC Oscillator Operating Modes
Note:
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
or Timer Oscillator pins..
Table 10. Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
Note:
SUT1..0
10
00
01
11
10. PB6 (XTAL1/TOSC1) and PB7(XTAL2/TOSC2) can be used as either general I/O pins
(1)
1. The device is shipped with this option selected
1. The device is shipped with this option selected
CKSEL3..0
0001
0010
0011
0100
Start-up Time from
Power-down and
(1)
Power-save
6 CK
6 CK
6 CK
“Calibration Byte” on page
Additional Delay
(V
from Reset
CC
Reserved
4.1ms
65ms
= 5.0V)
–
Nominal Frequency (MHz)
218.
1.0
2.0
4.0
8.0
Recommended Usage
BOD enabled
Fast rising power
Slowly rising power
Table
9. If selected, it will operate
CC
and Temperature.
2486Z–AVR–02/11