ATMEGA8A-AUR Atmel, ATMEGA8A-AUR Datasheet - Page 27

• Manufacturer Part Number: ATMEGA8A-AUR
• Description: MCU AVR 8KB FLASH 16MHZ 32TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8A-AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.4
8159D–AVR–02/11
Low-frequency Crystal Oscillator
Table 8-4.
Notes:
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 “1001”. The crystal should be con-
nected as shown in
capacitors on XTAL1 and XTAL2, thereby removing the need for external capacitors. The inter-
nal capacitors have a nominal value of 36 pF.
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 8-5.
Note:
CKSEL0
SUT1:0
00
01
10
11
0
0
0
0
1
1
1
1
8-5.
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
1. These options should only be used if frequency stability at start-up is not important for the
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.
application.
SUT1:0
Start-up Times for the Crystal Oscillator Clock Selection
Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
Start-up Time from
Power-down and
00
01
10
11
00
01
10
11
Power-save
1K CK
1K CK
Figure
32K CK
from Power-down
(1)
(1)
and Power-save
8-2. By programming the CKOPT Fuse, the user can enable internal
Start-up Time
258 CK
258 CK
1K CK
1K CK
1K CK
16K CK
16K CK
16K CK
(2)
(2)
(2)
(1)
(1)
Additional Delay
(V
from Reset
CC
4.1 ms
65 ms
65 ms
= 5.0V)
Additional Delay
Reserved
(V
from Reset
CC
4.1 ms
4.1 ms
4.1 ms
65 ms
65 ms
65 ms
= 5.0V)
–
–
Recommended Usage
Fast rising power or BOD enabled
Slowly rising power
Stable frequency at start-up
Recommended Usage
Ceramic resonator, fast rising
power
Ceramic resonator, slowly
rising power
Ceramic resonator, BOD
enabled
Ceramic resonator, fast rising
power
Ceramic resonator, slowly
rising power
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast rising
power
Crystal Oscillator, slowly
rising power
ATmega8A
27