ATmega8A Atmel Corporation, ATmega8A Datasheet - Page 28

• 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

8.5
8159D–AVR–02/11
External RC Oscillator
For timing insensitive applications, the external RC configuration shown in
used. The frequency is roughly estimated by the equation f = 1/(3RC). C should be at least 22
pF. By programming the CKOPT Fuse, the user can enable an internal 36 pF capacitor between
XTAL1 and GND, thereby removing the need for an external capacitor.
Figure 8-3.
The Oscillator can operate in four different modes, each optimized for a specific frequency
range. The operating mode is selected by the fuses CKSEL3:0 as shown in
Table 8-6.
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 8-7.
Note:
SUT1:0
00
01
10
11
8-7.
1. This option should not be used when operating close to the maximum frequency of the device.
CKSEL3:0
Start-up Time from
External RC Configuration
External RC Oscillator Operating Modes
Start-up Times for the External RC Oscillator Clock Selection
Power-down and
0101
0110
0111
1000
Power-save
6 CK
18 CK
18 CK
18 CK
(1)
R
C
V
CC
Additional Delay
(V
from Reset
NC
CC
4.1 ms
4.1 ms
65 ms
= 5.0V)
–
Frequency Range (MHz)
XTAL2
XTAL1
GND
Recommended Usage
BOD enabled
Fast rising power
Slowly rising power
Fast rising power or BOD enabled
8.0 - 12.0
0.1 - 0.9
0.9 - 3.0
3.0 - 8.0
ATmega8A
Table
Figure 8-3
8-6.
can be
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