ATmega8A Atmel Corporation, ATmega8A Datasheet - Page 29

• Manufacturer Part Number: ATmega8A
• Manufacturer: Atmel Corporation

Specifications of ATmega8A

• 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
• Pwm Channels: 3
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

8.6
8159D–AVR–02/11
Calibrated Internal RC Oscillator
The calibrated internal RC Oscillator provides a fixed 1.0, 2.0, 4.0, or 8.0MHz clock. All frequen-
cies 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
nal components. The CKOPT Fuse should always be unprogrammed when using this clock
option. During reset, hardware loads the 1MHz calibration byte into the OSCCAL Register 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 possi-
ble to achieve ± 1% accuracy at any given V
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 calibration value, see the section
“Calibration Byte” on page
Table 8-8.
Note:
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
pins or Timer Oscillator pins:
Table 8-9.
Note:
SUT1:0
10
00
01
11
8-9. PB6 (XTAL1/TOSC1) and PB7(XTAL2/TOSC2) can be used as either general I/O
(1)
1. The device is shipped with this option selected.
1. The device is shipped with this option selected.
CKSEL3:0
Internal Calibrated RC Oscillator Operating Modes
Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
0001
Power-down and Power-
0010
0011
0100
Start-up Time from
(1)
save
6 CK
6 CK
6 CK
228.
Additional Delay from
CC
Table
(V
and Temperature. When this Oscillator is used
CC
4.1 ms
Reserved
Reset
65 ms
8-8. If selected, it will operate with no exter-
= 5.0V)
–
Nominal Frequency (MHz)
1.0
2.0
4.0
8.0
Recommended Usage
BOD enabled
Fast rising power
Slowly rising power
ATmega8A
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